// src/nvserializer.ts
import { vec3 } from 'gl-matrix'
import { NVUtilities } from '@/nvutilities'
import { NVImage, NVIMAGE_TYPE } from '@/nvimage'
import { NVMesh, MeshType } from '@/nvmesh'
import { NVConnectome } from '@/nvconnectome'
import { log } from '@/logger'
import { NVDocument, DEFAULT_OPTIONS, DocumentData, ExportDocumentData, INITIAL_SCENE_DATA } from '@/nvdocument'
import { migrateLegacyDocument, normalizeMeshForRehydrate } from '@/utils/legacy-migrate' // shared migration utility

/** Helpers for special numeric encoding */
function encodeNumberForJSON(v: number | null | undefined): number | string | undefined {
    if (v === undefined) {
        return undefined
    }
    if (v === null) {
        return null
    }
    if (Number.isFinite(v)) {
        return v
    }
    if (v === Infinity) {
        return 'infinity'
    }
    if (v === -Infinity) {
        return '-infinity'
    }
    return 'NaN'
}
function decodeNumberFromJSON(v: any): number | null | undefined {
    if (v === undefined) {
        return undefined
    }
    if (v === null) {
        return null
    }
    if (typeof v === 'number') {
        return v
    }
    if (v === 'NaN') {
        return NaN
    }
    if (v === 'infinity') {
        return Infinity
    }
    if (v === '-infinity') {
        return -Infinity
    }
    const n = Number(v)
    return Number.isNaN(n) ? NaN : n
}

/** Small safe conversion helper that handles arrays, typed arrays, iterables. */
function toPlainArray<T>(maybe: any): T[] | undefined {
    if (maybe === undefined || maybe === null) {
        return undefined
    }
    if (Array.isArray(maybe)) {
        return maybe.slice()
    }
    try {
        // cast via unknown to satisfy TS when given typed arrays / arraybufferviews
        return Array.from(maybe as unknown as Iterable<T>)
    } catch (e) {
        return undefined
    }
}

/**
 * Convert array-like to Float32Array.
 * Returns undefined if input is null/undefined.
 */
function toFloat32Array(maybe: any): Float32Array | undefined {
    if (maybe === undefined || maybe === null) {
        return undefined
    }
    if (maybe instanceof Float32Array) {
        return maybe
    }
    if (Array.isArray(maybe)) {
        return new Float32Array(maybe)
    }
    if (ArrayBuffer.isView(maybe)) {
        return new Float32Array(Array.from(maybe as unknown as Iterable<number>))
    }
    try {
        return new Float32Array(Array.from(maybe as unknown as Iterable<number>))
    } catch (e) {
        return undefined
    }
}

/**
 * Convert array-like to Uint32Array.
 * Returns undefined if input is null/undefined.
 */
function toUint32Array(maybe: any): Uint32Array | undefined {
    if (maybe === undefined || maybe === null) {
        return undefined
    }
    if (maybe instanceof Uint32Array) {
        return maybe
    }
    if (Array.isArray(maybe)) {
        return new Uint32Array(maybe)
    }
    if (ArrayBuffer.isView(maybe)) {
        return new Uint32Array(Array.from(maybe as unknown as Iterable<number>))
    }
    try {
        return new Uint32Array(Array.from(maybe as unknown as Iterable<number>))
    } catch (e) {
        return undefined
    }
}

/**
 * Convert array-like to Uint8Array.
 * Returns undefined if input is null/undefined.
 */
function toUint8Array(maybe: any): Uint8Array | undefined {
    if (maybe === undefined || maybe === null) {
        return undefined
    }
    if (maybe instanceof Uint8Array) {
        return maybe
    }
    if (Array.isArray(maybe)) {
        return new Uint8Array(maybe)
    }
    if (ArrayBuffer.isView(maybe)) {
        return new Uint8Array(Array.from(maybe as unknown as Iterable<number>))
    }
    try {
        return new Uint8Array(Array.from(maybe as unknown as Iterable<number>))
    } catch (e) {
        return undefined
    }
}

/** replacer to convert typed arrays / array buffers to plain arrays for JSON.stringify */
function jsonReplacer(_key: string, value: any): any {
    if (typeof value === 'function') {
        return undefined
    }
    if (typeof value === 'symbol') {
        return undefined
    }

    // Typed arrays & DataView -> array of numbers
    if (ArrayBuffer.isView(value)) {
        if (value instanceof DataView) {
            return Array.from(new Uint8Array((value as DataView).buffer, (value as DataView).byteOffset, (value as DataView).byteLength))
        }
        // cast through unknown to avoid TS complaining about missing iterator
        return Array.from(value as unknown as Iterable<number>)
    }

    if (value instanceof ArrayBuffer) {
        return Array.from(new Uint8Array(value))
    }

    return value
}

export class NVSerializer {
    /**
     * Decode/normalize "opts" encoded form into NVConfigOptions shape.
     * Move the decodeOptsFromJSON logic here (serializer owns encoding/decoding).
     */
    static decodeOptsFromJSON(opts: any): any {
        if (opts === undefined || opts === null) {
            return undefined
        }

        const decodeRecursive = (v: any): any => {
            if (v === undefined) {
                return undefined
            }
            if (v === null) {
                return null
            }
            if (typeof v === 'number') {
                return v
            }
            if (typeof v === 'string') {
                // try to decode special numeric strings
                if (v === 'NaN') {
                    return NaN
                }
                if (v === 'infinity') {
                    return Infinity
                }
                if (v === '-infinity') {
                    return -Infinity
                }
                return v
            }
            if (Array.isArray(v)) {
                return v.map((el) => decodeRecursive(el))
            }
            if (typeof v === 'object') {
                const out: any = {}
                for (const k of Object.keys(v)) {
                    out[k] = decodeRecursive(v[k])
                }
                return out
            }
            return v
        }

        const out: any = {}
        for (const k of Object.keys(opts)) {
            const val = opts[k]
            if (val === undefined) {
                continue
            }
            out[k] = decodeRecursive(val)
        }
        return out
    }

    /**
     * Serialize an NVDocument-like object into ExportDocumentData (same shape as NVDocument.json)
     * (This function mirrors the responsibilities of NVDocument.json in your code).
     */
    static serializeDocument(document: any, embedImages = true, embedDrawing = true): ExportDocumentData {
        const out: Partial<ExportDocumentData> = {
            encodedImageBlobs: [],
            previewImageDataURL: document.previewImageDataURL ?? '',
            imageOptionsMap: new Map<string, number>()
        }

        out.sceneData = { ...(document.scene?.sceneData ?? {}) }
        out.opts = document.opts ?? {}
        out.labels = Array.isArray(document.labels)
            ? document.labels.map((l: any) => {
                  const copy = { ...(l || {}) }
                  delete copy.onClick
                  return copy
              })
            : []

        out.customData = document.customData ?? ''
        out.completedMeasurements = document.completedMeasurements ? document.completedMeasurements.slice() : []
        out.completedAngles = document.completedAngles ? document.completedAngles.slice() : []

        // images
        const imageOptionsArray: any[] = []
        const volumes = document.volumes ?? []
        if (volumes.length) {
            for (let i = 0; i < volumes.length; i++) {
                const v = volumes[i]
                let imageOptions = document.getImageOptions ? document.getImageOptions(v) : null
                if (imageOptions === null) {
                    // fallback minimal options
                    imageOptions = {
                        name: v?.name ?? '',
                        colormap: v?._colormap ?? 'gray',
                        opacity: v?._opacity ?? 1.0,
                        cal_min: v?.cal_min ?? NaN,
                        cal_max: v?.cal_max ?? NaN,
                        trustCalMinMax: v?.trustCalMinMax ?? true,
                        percentileFrac: v?.percentileFrac ?? 0.02,
                        ignoreZeroVoxels: v?.ignoreZeroVoxels ?? false,
                        imageType: v?.imageType ?? NVIMAGE_TYPE.NII,
                        frame4D: v?.frame4D ?? 0,
                        limitFrames4D: v?.limitFrames4D ?? NaN,
                        url: v?.url ?? '',
                        urlImageData: v?.urlImgData ?? '',
                        cal_minNeg: v?.cal_minNeg ?? NaN,
                        cal_maxNeg: v?.cal_maxNeg ?? NaN,
                        colorbarVisible: v?.colorbarVisible ?? true
                    }
                } else {
                    if (!('imageType' in imageOptions)) {
                        imageOptions.imageType = NVIMAGE_TYPE.NII
                    }
                }

                imageOptions.colormap = v.colormap
                imageOptions.colormapLabel = v.colormapLabel
                imageOptions.opacity = v.opacity
                imageOptions.cal_max = v.cal_max ?? NaN
                imageOptions.cal_min = v.cal_min ?? NaN

                imageOptionsArray.push(imageOptions)

                if (embedImages) {
                    const blob = NVUtilities.uint8tob64(v.toUint8Array())
                    out.encodedImageBlobs!.push(blob)
                }
                out.imageOptionsMap!.set(v.id, i)
            }
        }
        out.imageOptionsArray = imageOptionsArray

        // meshes: build safe clones and convert typed arrays to plain arrays
        const meshesForExport: any[] = []
        const meshes = document.meshes || []
        out.connectomes = []
        for (const mesh of meshes) {
            if (!mesh || typeof mesh !== 'object') {
                continue
            }
            if (mesh.type === MeshType.CONNECTOME) {
                try {
                    out.connectomes!.push(JSON.stringify((mesh as NVConnectome).json()))
                } catch (e) {
                    log.warn('serializeDocument: failed connectome export', e)
                }
                continue
            }

            // build layers
            const layersForExport = (mesh.layers || []).map((layer: any) => {
                const exported: any = {
                    name: layer?.name,
                    key: layer?.key,
                    url: layer?.url,
                    headers: layer?.headers,
                    opacity: layer?.opacity,
                    colormap: layer?.colorMap ?? layer?.colormap,
                    colormapNegative: layer?.colorMapNegative ?? layer?.colormapNegative,
                    colormapInvert: layer?.colormapInvert,
                    colormapLabel: layer?.colormapLabel,
                    useNegativeCmap: layer?.useNegativeCmap,
                    // numeric meta
                    global_min: encodeNumberForJSON(layer?.global_min),
                    global_max: encodeNumberForJSON(layer?.global_max),
                    cal_min: encodeNumberForJSON(layer?.cal_min),
                    cal_max: encodeNumberForJSON(layer?.cal_max),
                    cal_minNeg: encodeNumberForJSON(layer?.cal_minNeg),
                    cal_maxNeg: encodeNumberForJSON(layer?.cal_maxNeg),
                    isAdditiveBlend: layer?.isAdditiveBlend,
                    frame4D: layer?.frame4D,
                    nFrame4D: layer?.nFrame4D,
                    outlineBorder: layer?.outlineBorder,
                    isTransparentBelowCalMin: layer?.isTransparentBelowCalMin,
                    colormapType: layer?.colormapType,
                    base64: layer?.base64,
                    colorbarVisible: layer?.colorbarVisible,
                    showLegend: layer?.showLegend
                }

                if (layer?.values != null) {
                    const vals = Array.isArray(layer.values) ? layer.values.slice() : Array.from((layer.values as unknown as Iterable<number>) || [])
                    exported.values = vals.map((v: any) => {
                        const num = Number(v)
                        return Number.isFinite(num) ? Math.round(num * 1e12) / 1e12 : num
                    })
                }
                if (layer?.atlasValues != null) {
                    exported.atlasValues = Array.isArray(layer.atlasValues) ? layer.atlasValues.slice() : Array.from((layer.atlasValues as unknown as Iterable<number>) || [])
                }
                if (Array.isArray(layer?.labels)) {
                    exported.labels = layer.labels.map((l: any) => ({ ...(l || {}) }))
                } else if (layer?.labels != null) {
                    exported.labels = Array.from((layer.labels as unknown as Iterable<any>) || [])
                }
                return exported
            })

            const meshCopy: any = {
                ...Object.assign({}, mesh || {}),
                rgba255: Array.from(mesh.rgba255 || []),
                layers: layersForExport,
                edges: Array.isArray(mesh?.edges) ? mesh.edges.map((e: any) => ({ ...(e || {}) })) : [],
                nodes: Array.isArray(mesh?.nodes) ? mesh.nodes.map((n: any) => ({ ...(n || {}) })) : mesh?.nodes,
                offsetPt0: Array.isArray(mesh?.offsetPt0) ? [...mesh.offsetPt0] : mesh?.offsetPt0
            }

            // fiber fields
            if (Array.isArray(mesh.offsetPt0) && mesh.offsetPt0.length > 0) {
                meshCopy.offsetPt0 = Array.isArray(mesh.offsetPt0) ? [...mesh.offsetPt0] : mesh.offsetPt0
                if (Array.isArray(mesh.fiberGroupColormap)) {
                    meshCopy.fiberGroupColormap = [...mesh.fiberGroupColormap]
                }
                if (Array.isArray(mesh.fiberColor)) {
                    meshCopy.fiberColor = Array.from(mesh.fiberColor)
                }
                meshCopy.fiberDither = mesh.fiberDither
                meshCopy.fiberRadius = mesh.fiberRadius
                meshCopy.colormap = mesh.colormap
            }

            meshesForExport.push(meshCopy)
        }

        try {
            out.meshesString = JSON.stringify(meshesForExport, jsonReplacer)
        } catch (err) {
            log.warn('serializeDocument: JSON.stringify failed for meshes', err)
            // fallback: per-mesh serialization
            const per: string[] = []
            for (let i = 0; i < meshesForExport.length; i++) {
                try {
                    per.push(JSON.stringify(meshesForExport[i], jsonReplacer))
                } catch (e) {
                    log.error('serializeDocument: failed to serialize mesh at index', i, e, meshesForExport[i])
                    per.push(JSON.stringify({ name: meshesForExport[i]?.name ?? 'unknown', id: meshesForExport[i]?.id ?? null }))
                }
            }
            out.meshesString = `[${per.join(',')}]`
        }

        if (embedDrawing && document.drawBitmap) {
            out.encodedDrawingBlob = NVUtilities.uint8tob64(document.drawBitmap)
        } else {
            out.encodedDrawingBlob = document.encodedDrawingBlob ?? ''
        }

        out.title = document.title ?? 'untitled'
        out.customData = document.customData ?? ''
        out.labels = Array.isArray(document.labels)
            ? document.labels.map((l: any) => {
                  const copy = { ...(l || {}) }
                  delete copy.onClick
                  return copy
              })
            : []

        // Export completed measurements & angles (clone vectors/objects so they survive JSON roundtrip)
        out.completedMeasurements = (document.completedMeasurements || []).map((m: any) => ({
            ...m,
            startMM: Array.isArray(m.startMM) ? [...m.startMM] : m.startMM,
            endMM: Array.isArray(m.endMM) ? [...m.endMM] : m.endMM
        }))

        out.completedAngles = (document.completedAngles || []).map((a: any) => ({
            ...a,
            firstLineMM: {
                start: Array.isArray(a.firstLineMM?.start) ? [...a.firstLineMM.start] : a.firstLineMM?.start,
                end: Array.isArray(a.firstLineMM?.end) ? [...a.firstLineMM.end] : a.firstLineMM?.end
            },
            secondLineMM: {
                start: Array.isArray(a.secondLineMM?.start) ? [...a.secondLineMM.start] : a.secondLineMM?.start,
                end: Array.isArray(a.secondLineMM?.end) ? [...a.secondLineMM.end] : a.secondLineMM?.end
            }
        }))

        // Make sure sceneData and opts are included (you already had these, but double-check)
        out.sceneData = out.sceneData ?? { ...(document.scene?.sceneData ?? {}) }
        out.opts = out.opts ?? (document.opts ? { ...(document.opts as any) } : {})

        return out as ExportDocumentData
    }

    /**
     * Rehydrate images into NVImage instances using NVImage.new
     */
    static async rehydrateImages(documentData: DocumentData): Promise<NVImage[]> {
        const imgs: NVImage[] = []

        // Normalize legacy shapes first
        const migrated = await migrateLegacyDocument(documentData)

        const encoded = migrated.encodedImageBlobs ?? []
        const optsArr = migrated.imageOptionsArray ?? []

        for (let i = 0; i < optsArr.length; i++) {
            const imageOptions = { ...(optsArr[i] || {}) } as any
            try {
                const b64 = encoded[i]
                if (!b64) {
                    log.debug('NVSerializer.rehydrateImages: no blob for index', i)
                    continue
                }
                const u8 = await NVUtilities.b64toUint8(b64)
                if (!u8) {
                    log.warn('NVSerializer.rehydrateImages: b64toUint8 returned empty for index', i)
                    continue
                }

                const name = imageOptions.name ?? imageOptions.url ?? `image-${i}`
                // Ensure colormap keys are strings when we call color-table lookups.
                // Legacy data sometimes stores colormaps in typed-array / object shapes —
                // guard against that so colormapFromKey(name) doesn't throw.
                let colormap: string | any[] = imageOptions.colormap ?? imageOptions.colorMap ?? ''
                if (typeof colormap !== 'string') {
                    // Prefer the explicitly provided colorMap string if present
                    if (typeof imageOptions.colorMap === 'string') {
                        colormap = imageOptions.colorMap
                    } else {
                        // otherwise treat as "no named colormap" so colour-table lookup won't be attempted
                        colormap = ''
                    }
                }

                const opacity = imageOptions.opacity ?? 1.0

                const pairedImgData = imageOptions.pairedImgData
                    ? typeof imageOptions.pairedImgData === 'string'
                        ? (await NVUtilities.b64toUint8(imageOptions.pairedImgData)).buffer
                        : imageOptions.pairedImgData
                    : null
                const cal_min = decodeNumberFromJSON(imageOptions.cal_min)
                const cal_max = decodeNumberFromJSON(imageOptions.cal_max)
                const trustCalMinMax = imageOptions.trustCalMinMax ?? true
                const percentileFrac = imageOptions.percentileFrac ?? 0.02
                const ignoreZeroVoxels = imageOptions.ignoreZeroVoxels ?? false
                const useQFormNotSForm = imageOptions.useQFormNotSForm ?? false
                const colormapNegative = imageOptions.colormapNegative ?? ''
                const frame4D = imageOptions.frame4D ?? 0
                const imageType = 'imageType' in imageOptions && typeof imageOptions.imageType === 'number' ? imageOptions.imageType : (imageOptions.imageType ?? NVIMAGE_TYPE.UNKNOWN)
                const cal_minNeg = decodeNumberFromJSON(imageOptions.cal_minNeg)
                const cal_maxNeg = decodeNumberFromJSON(imageOptions.cal_maxNeg)
                const colorbarVisible = imageOptions.colorbarVisible ?? true
                const colormapLabel = imageOptions.colormapLabel ?? null
                const colormapType = imageOptions.colormapType ?? 0
                const zarrData = imageOptions.zarrData ?? null

                // ensure ArrayBuffer argument
                console.log(`Image ${i} buffer length: ${u8.byteLength}`)

                // Check if the data is actually all zeros before Niivue gets it
                const isAllZeros = !u8.some((val) => val !== 0)
                if (isAllZeros) {
                    console.error(`CRITICAL: Base64 decoding for ${name} resulted in an all-zero array!`)
                }

                const bufferArg = u8.slice().buffer

                const img = await NVImage.new(
                    bufferArg,
                    name,
                    colormap as string,
                    opacity,
                    pairedImgData,
                    cal_min as any,
                    cal_max as any,
                    trustCalMinMax,
                    percentileFrac,
                    ignoreZeroVoxels,
                    useQFormNotSForm,
                    colormapNegative,
                    frame4D,
                    imageType,
                    cal_minNeg as any,
                    cal_maxNeg as any,
                    colorbarVisible,
                    colormapLabel,
                    colormapType,
                    zarrData
                )
                imgs.push(img)
            } catch (err) {
                log.warn('NVSerializer.rehydrateImages: failed for index', i, err)
            }
        }
        return imgs
    }

    /**
     * Rehydrate meshes into runtime NVMesh instances.
     * If gl is provided and callUpdateMesh=true, updateMesh(gl) will be called.
     *
     * CRITICAL FIX: Properly convert arrays to TypedArrays before passing to NVMesh constructor
     * to avoid "underspecified mesh" warnings.
     */
    static async rehydrateMeshes(documentData: DocumentData, gl?: WebGL2RenderingContext, callUpdateMesh = false): Promise<Array<NVMesh | any>> {
        const out: Array<NVMesh | any> = []

        // Normalize legacy shapes first
        const migrated = await migrateLegacyDocument(documentData)

        const meshesString = migrated.meshesString ?? '[]'

        let parsed: any[] = []
        try {
            parsed = JSON.parse(meshesString)
        } catch (e) {
            console.warn('NVSerializer.rehydrateMeshes: failed to parse meshesString', e)
            parsed = []
        }

        for (let i = 0; i < parsed.length; i++) {
            let m = parsed[i] || {}
            try {
                m = normalizeMeshForRehydrate(m)
                // Normalize layer keys and numeric encodings (colorMap -> colormap etc.)
                if (Array.isArray(m.layers)) {
                    for (const layer of m.layers) {
                        if (!layer) {
                            continue
                        }
                        if ('colorMap' in layer && !('colormap' in layer)) {
                            layer.colormap = layer.colorMap
                            delete layer.colorMap
                        }
                        if ('colorMapNegative' in layer && !('colormapNegative' in layer)) {
                            layer.colormapNegative = layer.colorMapNegative
                            delete layer.colorMapNegative
                        }

                        // decode special numeric strings (in case encodeNumberForJSON used)
                        layer.global_min = decodeNumberFromJSON(layer.global_min)
                        layer.global_max = decodeNumberFromJSON(layer.global_max)
                        layer.cal_min = decodeNumberFromJSON(layer.cal_min)
                        layer.cal_max = decodeNumberFromJSON(layer.cal_max)
                        layer.cal_minNeg = decodeNumberFromJSON(layer.cal_minNeg)
                        layer.cal_maxNeg = decodeNumberFromJSON(layer.cal_maxNeg)

                        // ensure values/atlasValues are plain arrays (migration already attempted to normalize)
                        if (layer.values != null && !Array.isArray(layer.values)) {
                            try {
                                layer.values = Array.from(layer.values)
                            } catch (e) {
                                /* leave as-is */
                            }
                        }
                        if (layer.atlasValues != null && !Array.isArray(layer.atlasValues)) {
                            try {
                                layer.atlasValues = Array.from(layer.atlasValues)
                            } catch (e) {
                                /* leave as-is */
                            }
                        }
                    }
                }

                // CRITICAL: Convert arrays to proper TypedArrays BEFORE creating NVMesh
                // This prevents the "underspecified mesh" warning in updateMesh

                // Convert rgba255 to Uint8Array
                const rgba255 = toUint8Array(m.rgba255) ?? new Uint8Array([255, 255, 255, 255])

                // Convert pts to Float32Array (vertex positions)
                const pts = toFloat32Array(m.pts)

                // Convert tris to Uint32Array (triangle indices)
                let tris = toUint32Array(m.tris)

                // ensure nodes/edges plain arrays
                if (Array.isArray(m.nodes)) {
                    m.nodes = m.nodes.length > 0 && typeof m.nodes[0] === 'object' ? m.nodes.map((n: any) => ({ ...n })) : m.nodes.slice()
                }
                if (Array.isArray(m.edges)) {
                    m.edges = m.edges.length > 0 && typeof m.edges[0] === 'object' ? m.edges.map((e: any) => ({ ...e })) : m.edges.slice()
                }

                // preserve id if present (important)
                const persistedId = m.id !== undefined ? m.id : null

                // If no GL provided, keep as plain object (tests may parse/expect object form)
                if (!gl) {
                    // For test environments, keep arrays as-is
                    out.push(m)
                    continue
                }

                // Handle fiber meshes: offsetPt0 becomes tris
                if (Array.isArray(m.offsetPt0) && m.offsetPt0.length > 0) {
                    tris = new Uint32Array(m.offsetPt0)
                    // Set alpha to 0 for fibers
                    if (rgba255) {
                        rgba255[3] = 0
                    }
                }

                // produce a plain Uint8Array backed by ArrayBuffer
                const finalizedRgba = new Uint8Array(Array.isArray(rgba255) ? rgba255 : Array.from(rgba255 as Uint8Array))

                const meshInstance = new NVMesh(pts, tris, m.name, finalizedRgba, m.opacity, m.visible, gl, m.connectome, m.dpg, m.dps, m.dpv)

                // restore preserved id (overwrite generated id)
                if (persistedId !== null) {
                    ;(meshInstance as any).id = persistedId
                }

                // fiber metadata
                if (Array.isArray(m.offsetPt0) && m.offsetPt0.length > 0) {
                    meshInstance.fiberGroupColormap = m.fiberGroupColormap
                    meshInstance.fiberColor = m.fiberColor ? m.fiberColor : undefined
                    meshInstance.fiberDither = m.fiberDither
                    meshInstance.fiberRadius = m.fiberRadius
                    meshInstance.colormap = m.colormap
                }

                // layers & shader index
                meshInstance.meshShaderIndex = m.meshShaderIndex
                meshInstance.layers = m.layers || []

                if (callUpdateMesh) {
                    try {
                        meshInstance.updateMesh(gl)
                    } catch (e) {
                        console.warn('NVSerializer.rehydrateMeshes: updateMesh failed for idx', i, e)
                    }
                }

                out.push(meshInstance)
            } catch (err) {
                console.warn('NVSerializer.rehydrateMeshes: failed idx', i, err)
                // push the plain object as fallback so lengths/indices remain stable
                out.push(m)
            }
        }

        // Defensive: guarantee an array is returned for all (possibly-legacy) inputs.
        try {
            // Defensive: guarantee an array is returned for all (possibly-legacy) inputs.
            if (!Array.isArray(out)) {
                console.warn('NVSerializer.rehydrateMeshes: unexpected non-array output, coercing to array', {
                    typeofOut: typeof out,
                    isArray: Array.isArray(out),
                    outPreview: out && (typeof out === 'object' ? Object.keys(out).slice(0, 10) : out)
                })
                return out ? [out] : []
            }

            return out
        } catch (err) {
            console.error('NVSerializer.rehydrateMeshes: final-return error', err)
            return []
        }
    }

    static async deserializeDocument(documentData: DocumentData): Promise<NVDocument> {
        // run migration to normalize legacy shapes up-front
        const migrated = await migrateLegacyDocument(documentData)

        // Create a fresh NVDocument
        const document = new NVDocument()

        // Basic top-level fields (preserve defaults where missing)
        Object.assign(document.data, {
            ...migrated,
            imageOptionsArray: migrated.imageOptionsArray ?? [],
            encodedImageBlobs: migrated.encodedImageBlobs ?? [],
            labels: migrated.labels ?? [],
            meshOptionsArray: migrated.meshOptionsArray ?? [],
            connectomes: migrated.connectomes ?? [],
            encodedDrawingBlob: migrated.encodedDrawingBlob ?? '',
            previewImageDataURL: migrated.previewImageDataURL ?? '',
            customData: migrated.customData ?? '',
            title: migrated.title ?? 'untitled'
        })

        // decode opts and merge with defaults
        const decodedOpts = NVSerializer.decodeOptsFromJSON((migrated as any).opts as any)
        document.data.opts = {
            ...DEFAULT_OPTIONS,
            ...(decodedOpts || {})
        } as any

        if ((document.data.opts as any).meshThicknessOn2D === 'infinity') {
            ;(document.data.opts as any).meshThicknessOn2D = Infinity
        }

        // scene data (merge with initial scene)
        document.scene.sceneData = {
            ...INITIAL_SCENE_DATA,
            ...(migrated.sceneData || {})
        }

        // back-compat: single clipPlane fields -> arrays
        const sceneDataAny: any = migrated.sceneData || {}
        if (sceneDataAny.clipPlane && !sceneDataAny.clipPlanes) {
            document.scene.sceneData.clipPlanes = [sceneDataAny.clipPlane]
        }
        if (sceneDataAny.clipPlaneDepthAziElev && !sceneDataAny.clipPlaneDepthAziElevs) {
            document.scene.sceneData.clipPlaneDepthAziElevs = [sceneDataAny.clipPlaneDepthAziElev]
        }

        // restore completed measurements & angles (clone vectors)
        if (migrated.completedMeasurements) {
            document.completedMeasurements = migrated.completedMeasurements.map((m: any) => ({
                ...m,
                startMM: vec3.clone(m.startMM),
                endMM: vec3.clone(m.endMM)
            }))
        }
        if (migrated.completedAngles) {
            document.completedAngles = migrated.completedAngles.map((a: any) => ({
                ...a,
                firstLineMM: {
                    start: vec3.clone(a.firstLineMM.start),
                    end: vec3.clone(a.firstLineMM.end)
                },
                secondLineMM: {
                    start: vec3.clone(a.secondLineMM.start),
                    end: vec3.clone(a.secondLineMM.end)
                }
            }))
        }

        // keep other runtime lists in sync
        // preserve connectome strings (Niivue.loadDocument adds them as runtime meshes later)
        document.data.connectomes = migrated.connectomes ?? []

        // drawing blob stays as encoded base64 (consumer will decode)
        document.data.encodedDrawingBlob = migrated.encodedDrawingBlob ?? ''

        // preview image
        document.data.previewImageDataURL = migrated.previewImageDataURL ?? ''

        return document
    }
}

export default NVSerializer