import {useMemo} from 'react'

import {useDeeplink} from '../navigation/useDeeplink'

/**
 * Structured description of an intent, following the Shopify Intents API
 * URI format: `action:type,value`
 *
 * @see https://shopify.dev/docs/api/admin-extensions/latest/target-apis/utility-apis/intents-api
 */
export interface IntentQuery {
  /** Verb describing the operation (e.g., 'try_on', 'create', 'edit') */
  action: string
  /** Resource type identifier (e.g., 'shopify/Product', 'shop/UserImage') */
  type: string
  /** Resource GID (e.g., 'gid://shopify/Product/123') if applicable */
  value: string | null
}

export interface UseIntentReturn {
  /** Parsed intent query, or null if no intent was passed */
  query: IntentQuery | null
  /** Additional JSON data passed with the intent, or null */
  data: {[key: string]: unknown} | null
}

/**
 * Parses an intent passed to this mini via deeplink.
 *
 * Follows the Shopify Intents API URI format (`action:type,value`) with
 * an optional JSON data payload passed separately.
 *
 * @see https://shopify.dev/docs/api/admin-extensions/latest/target-apis/utility-apis/intents-api
 *
 * Deeplink format:
 *   ?intentQuery=action:type,value&intentData={"key":"value"}
 *
 * Examples:
 *   ?intentQuery=try_on:shopify/Product,gid://shopify/Product/123
 *   ?intentQuery=create:shopify/Product
 *   ?intentQuery=edit:shopify/Product,gid://shopify/Product/123&intentData={"variantId":"456"}
 *
 * Shorthand GID syntax (type inferred from GID):
 *   ?intentQuery=edit:gid://shopify/Product/123
 *   ?intentQuery=create:gid://shopify/Product
 *
 * Use this hook to receive intents from the host app (Host → Mini direction).
 */
export function useIntent(): UseIntentReturn {
  const {queryParams} = useDeeplink()

  return useMemo(() => {
    const raw = queryParams?.intentQuery

    if (!raw) return {query: null, data: null}

    let decoded: string
    try {
      decoded = decodeURIComponent(raw)
    } catch {
      decoded = raw
    }

    const colonIdx = decoded.indexOf(':')
    if (colonIdx === -1) return {query: null, data: null}

    const action = decoded.slice(0, colonIdx)
    if (!action) return {query: null, data: null}

    const rest = decoded.slice(colonIdx + 1)
    const commaIdx = rest.indexOf(',')

    let type = commaIdx === -1 ? rest : rest.slice(0, commaIdx)
    let value = commaIdx === -1 ? null : rest.slice(commaIdx + 1) || null

    // Shorthand GID syntax: edit:gid://shopify/Product/123
    // Infer type from GID and use full GID as value
    const gidMatch = type.match(/^gid:\/\/shopify\/(\w+)(?:\/(.+))?$/)
    if (gidMatch) {
      type = `shopify/${gidMatch[1]}`
      value = gidMatch[2] ? `gid://shopify/${gidMatch[1]}/${gidMatch[2]}` : null
    }

    if (!type) return {query: null, data: null}

    let data: {[key: string]: unknown} | null = null
    const rawData = queryParams?.intentData
    if (rawData) {
      let parsed: unknown
      try {
        parsed = JSON.parse(rawData)
      } catch {
        try {
          parsed = JSON.parse(decodeURIComponent(rawData))
        } catch {
          // malformed JSON — ignore
        }
      }
      if (
        parsed !== null &&
        typeof parsed === 'object' &&
        !Array.isArray(parsed)
      ) {
        data = parsed as {[key: string]: unknown}
      }
    }

    return {
      query: {action, type, value},
      data,
    }
  }, [queryParams])
}

/**
 * Parses an intent passed to the Mini via deeplink, following the [Shopify Intents API](https://shopify.dev/docs/api/admin-extensions/latest/target-apis/utility-apis/intents-api) URI format (`action:type,value`). Returns the parsed `query` (`action`, `type`, `value`) and optional `data` payload. Use this hook to receive intents from the host app (Host → Mini direction), for example when the Shop app launches a Mini to handle a virtual try-on for a specific product.
 * @publicDocs
 */
export type UseIntentGeneratedType = () => UseIntentReturn