import { newRxError, newRxFetchError } from '../../rx-error.ts';
import { ensureNotFalsy } from '../utils/index.ts';
import type {
    GoogleDriveOptionsWithDefaults,
    DriveFileMetadata
} from './google-drive-types.ts';
import { DriveStructure } from './init.ts';

export const DRIVE_API_VERSION = 'v3';
export const DRIVE_MAX_PAGE_SIZE = 1000;
export const DRIVE_MAX_BULK_SIZE = DRIVE_MAX_PAGE_SIZE / 4;
export const FOLDER_MIME_TYPE = 'application/vnd.google-apps.folder';

/**
 * The id of the top level parent for the configured space.
 * For 'appDataFolder' this is the literal 'appDataFolder' which Google Drive
 * accepts as a parent id and in queries. For 'drive' it is the regular 'root'.
 */
export function driveRootParentId(
    googleDriveOptions: GoogleDriveOptionsWithDefaults
): string {
    return googleDriveOptions.space === 'appDataFolder' ? 'appDataFolder' : 'root';
}

/**
 * files.list only returns appDataFolder contents when spaces=appDataFolder
 * is set, even when querying by an explicit parent id.
 */
export function applyDriveSpace(
    googleDriveOptions: GoogleDriveOptionsWithDefaults,
    params: URLSearchParams
): void {
    if (googleDriveOptions.space === 'appDataFolder') {
        params.set('spaces', 'appDataFolder');
    }
}

/**
 * Same as applyDriveSpace() but for URLs that are built via string concatenation.
 * Returns an empty string for the default 'drive' space.
 */
export function driveSpaceQuerySuffix(
    googleDriveOptions: GoogleDriveOptionsWithDefaults
): string {
    return googleDriveOptions.space === 'appDataFolder' ? '&spaces=appDataFolder' : '';
}

export async function createFolder(
    googleDriveOptions: GoogleDriveOptionsWithDefaults,
    parentId: string = 'root',
    folderName: string
): Promise<string> {
    const url = googleDriveOptions.apiEndpoint + '/drive/v3/files?fields=id,name,mimeType,trashed';
    const body = {
        name: folderName,
        mimeType: FOLDER_MIME_TYPE,
        parents: [parentId]
    };

    const response = await fetch(url, {
        method: 'POST',
        headers: {
            Authorization: 'Bearer ' + googleDriveOptions.authToken,
            'Content-Type': 'application/json'
        },
        body: JSON.stringify(body)
    });

    if (!response.ok) {
        const errorText = await response.text();

        if (response.status == 409) {
            // someone else created the same folder, return that one instead.
            const found = await findFolder(googleDriveOptions, parentId, folderName);
            return ensureNotFalsy(found);
        }

        throw await newRxFetchError(response, {
            folderName,
            parentId
        });
    }

    await response.json();

    /**
     * To make the function idempotent, we do not use the id from the creation-response.
     * Instead after creating the folder, we search for it again so that in case
     * some other instance created the same folder, we use the oldest one always.
     */
    const foundFolder = await findFolder(
        googleDriveOptions,
        parentId,
        folderName
    );

    return ensureNotFalsy(foundFolder);
}


export async function findFolder(
    googleDriveOptions: GoogleDriveOptionsWithDefaults,
    parentId: string = 'root',
    folderName: string
): Promise<string | undefined> {
    const query = "name = '" + folderName + "' and '" + parentId + "' in parents and trashed = false and mimeType = '" + FOLDER_MIME_TYPE + "'";
    /**
     * We sort by createdTime ASC
     * so in case the same folder was created multiple times, we always pick the same
     * one which is the oldest one.
     */
    const searchUrl = googleDriveOptions.apiEndpoint + '/drive/v3/files?fields=files(id,mimeType)&orderBy=createdTime asc&q=' + encodeURIComponent(query) + driveSpaceQuerySuffix(googleDriveOptions);
    const searchResponse = await fetch(searchUrl, {
        method: 'GET',
        headers: {
            Authorization: 'Bearer ' + googleDriveOptions.authToken
        }
    });
    const searchData = await searchResponse.json();

    if (searchData.files && searchData.files.length > 0) {
        const file = searchData.files[0];
        if (file.mimeType !== FOLDER_MIME_TYPE) {
            throw newRxError('GDR3', {
                folderName,
                args: {
                    file,
                    FOLDER_MIME_TYPE
                }
            });
        }
        return file.id;
    } else {
        return undefined;
    }
}

export async function ensureFolderExists(
    googleDriveOptions: GoogleDriveOptionsWithDefaults,
    folderPath: string
): Promise<string> {
    const parts = folderPath.split('/').filter(p => p.length > 0);
    let parentId = driveRootParentId(googleDriveOptions);
    for (const part of parts) {
        const newParentId = await findFolder(googleDriveOptions, parentId, part);
        if (newParentId) {
            parentId = newParentId
        } else {
            parentId = await createFolder(googleDriveOptions, parentId, part);
        }
    }
    return parentId;
}


export async function createEmptyFile(
    googleDriveOptions: GoogleDriveOptionsWithDefaults,
    parentId: string,
    fileName: string
) {
    const url = googleDriveOptions.apiEndpoint + '/drive/v3/files?fields=id';
    const body = {
        name: fileName,
        parents: [parentId],
        mimeType: 'application/json'
    };

    const response = await fetch(url, {
        method: 'POST',
        headers: {
            Authorization: 'Bearer ' + googleDriveOptions.authToken,
            'Content-Type': 'application/json'
        },
        body: JSON.stringify(body)
    });

    /**
     * Do not throw on duplicates,
     * if the file is there already, find its id
     * and return that one.
     */
    if (!response.ok && response.status !== 409) {
        throw await newRxFetchError(response, {
            folderName: fileName
        });
    }

    /**
     * For idempotent runs, fetch the file again
     * after creating it.
     */
    const query = [
        `name = '${fileName}'`,
        `'${parentId}' in parents`,
        `trashed = false`,
    ].join(' and ');
    const url2 =
        googleDriveOptions.apiEndpoint + '/drive/v3/files' +
        '?fields=files(id)' +
        '&orderBy=createdTime asc' +
        '&q=' + encodeURIComponent(query) +
        driveSpaceQuerySuffix(googleDriveOptions);
    const res = await fetch(url2, {
        headers: {
            Authorization: 'Bearer ' + googleDriveOptions.authToken,
        },
    });
    const data = await res.json();
    const fileId = ensureNotFalsy(data.files[0]?.id);

    /**
     * Fetch the file metadata via v2 to get the etag (from the ETag response header)
     * and the file size atomically in a single request.
     * This avoids a race condition where the etag could change between
     * the file listing and a separate etag fetch.
     */
    const meta = await getFileMetadataV2(googleDriveOptions, fileId);
    return {
        status: response.status,
        etag: meta.etag,
        createdTime: meta.createdTime,
        fileId,
        size: meta.size
    };
}


/**
 * Fetches file metadata from the Google Drive v2 API.
 * Returns the etag (from the ETag response header), size, and createdTime
 * in a single atomic request.
 *
 * Note: the v2 API uses "createdDate" and "fileSize" as field names;
 * this function maps them to "createdTime" and "size" for consistency
 * with the rest of the codebase.
 */
async function getFileMetadataV2(
    googleDriveOptions: GoogleDriveOptionsWithDefaults,
    fileId: string
): Promise<{ etag: string; size: number; createdTime: string }> {
    const url =
        googleDriveOptions.apiEndpoint +
        `/drive/v2/files/${encodeURIComponent(fileId)}`;
    const res = await fetch(url, {
        headers: {
            Authorization: `Bearer ${googleDriveOptions.authToken}`,
        },
    });
    if (!res.ok) {
        throw await newRxFetchError(res, { args: { fileId } });
    }
    const meta = await res.json();
    return {
        etag: ensureNotFalsy(res.headers.get('ETag'), 'ETag missing'),
        // v2 uses "fileSize" and "createdDate" instead of the v3 "size" and "createdTime"
        size: parseInt(meta.fileSize ?? '0', 10),
        createdTime: ensureNotFalsy(meta.createdDate)
    };
}


export async function getFileEtag(
    googleDriveOptions: GoogleDriveOptionsWithDefaults,
    fileId: string
): Promise<string> {
    const meta = await getFileMetadataV2(googleDriveOptions, fileId);
    return meta.etag;
}

export async function fillFileIfEtagMatches<T = any>(
    googleDriveOptions: GoogleDriveOptionsWithDefaults,
    fileId: string,
    etag: string,
    jsonContent?: any
): Promise<{
    status: number;
    etag: string;
    content: T | undefined;
    serverTime: number;
}> {
    const url =
        `${googleDriveOptions.apiEndpoint}` +
        `/upload/drive/v2/files/${encodeURIComponent(fileId)}` +
        `?uploadType=media`;

    const writeContent = typeof jsonContent !== 'undefined' ? JSON.stringify(jsonContent) : '';
    const res = await fetch(url, {
        method: "PUT",
        headers: {
            Authorization: `Bearer ${googleDriveOptions.authToken}`,
            "Content-Type": "application/json; charset=utf-8",
            "If-Match": etag,
        },
        body: writeContent,
    });
    if (res.status !== 412 && res.status !== 200) {
        throw await newRxFetchError(res);
    }

    return readJsonFileContent<T>(
        googleDriveOptions,
        fileId
    ).then(r => {
        return {
            content: r.content,
            etag: r.etag,
            status: res.status,
            serverTime: r.serverTime
        };
    });
}

export async function deleteIfEtagMatches(
    googleDriveOptions: GoogleDriveOptionsWithDefaults,
    fileId: string,
    etag: string
): Promise<void> {
    const url =
        `${googleDriveOptions.apiEndpoint}` +
        `/drive/v2/files/${encodeURIComponent(fileId)}`;

    const res = await fetch(url, {
        method: "DELETE",
        headers: {
            Authorization: `Bearer ${googleDriveOptions.authToken}`,
            "If-Match": etag,
        },
    });

    if (!res.ok) {
        throw await newRxFetchError(res, {
            args: {
                etag,
                fileId
            }
        });
    }

    if (res.ok) {
        // Drive v2 returns 204 No Content on successful delete
        return;
    }
}

export async function deleteFile(
    googleDriveOptions: GoogleDriveOptionsWithDefaults,
    fileId: string
): Promise<void> {
    const url =
        `${googleDriveOptions.apiEndpoint}` +
        `/drive/v2/files/${encodeURIComponent(fileId)}`;

    const res = await fetch(url, {
        method: "DELETE",
        headers: {
            Authorization: `Bearer ${googleDriveOptions.authToken}`,
        },
    });

    if (!res.ok) {
        throw await newRxFetchError(res, {
            args: {
                fileId
            }
        });
    }

    if (res.ok) {
        // Drive v2 returns 204 No Content on successful delete
        return;
    }
}

export async function readJsonFileContent<T>(
    googleDriveOptions: GoogleDriveOptionsWithDefaults,
    fileId: string
): Promise<{
    etag: string;
    content: T | undefined;
    serverTime: number;
}> {
    const url =
        `${googleDriveOptions.apiEndpoint}` +
        `/drive/v2/files/${encodeURIComponent(fileId)}?alt=media`;

    const res = await fetch(url, {
        method: "GET",
        headers: {
            Authorization: `Bearer ${googleDriveOptions.authToken}`,
            Accept: "application/json",
        },
    });

    if (!res.ok) {
        throw await newRxFetchError(res, {
            args: {
                fileId
            }
        });
    }

    const dateHeader = res.headers.get('date');
    const unixMs = Date.parse(ensureNotFalsy(dateHeader));

    const contentType = res.headers.get("content-type") || "";
    if (!contentType.includes("application/json")) {
        const err = new Error("NOT_A_JSON_FILE but " + contentType);
        (err as any).code = "NOT_A_JSON_FILE";
        (err as any).contentType = contentType;
        throw err;
    }

    const contentText = await res.text();
    const content = contentText.length > 0 ? JSON.parse(contentText) : undefined;
    const etag = ensureNotFalsy(res.headers.get('etag'));
    return {
        etag,
        content: content as T,
        serverTime: unixMs
    };
}


export async function readFolder(
    googleDriveOptions: GoogleDriveOptionsWithDefaults,
    folderPath: string
): Promise<DriveFileMetadata[]> {
    let parentId = driveRootParentId(googleDriveOptions);
    const parts = folderPath.split('/').filter(p => p.length > 0);

    // Resolve folder path
    for (const part of parts) {
        const query = "name = '" + part + "' and '" + parentId + "' in parents and trashed = false and mimeType = '" + FOLDER_MIME_TYPE + "'";
        const searchUrl = googleDriveOptions.apiEndpoint + '/drive/v3/files?fields=files(id)&q=' + encodeURIComponent(query) + driveSpaceQuerySuffix(googleDriveOptions);
        const searchResponse = await fetch(searchUrl, {
            method: 'GET',
            headers: {
                Authorization: 'Bearer ' + googleDriveOptions.authToken
            }
        });
        const searchData = await searchResponse.json();
        if (searchData.files && searchData.files.length > 0) {
            parentId = searchData.files[0].id;
        } else {
            throw newRxError('SNH', { folderPath });
        }
    }

    // List children
    const query = "'" + parentId + "' in parents and trashed = false";
    const listUrl = googleDriveOptions.apiEndpoint + '/drive/v3/files?fields=files(id,name,mimeType,trashed,parents)&q=' + encodeURIComponent(query) + driveSpaceQuerySuffix(googleDriveOptions);
    const listResponse = await fetch(listUrl, {
        method: 'GET',
        headers: {
            Authorization: 'Bearer ' + googleDriveOptions.authToken
        }
    });

    if (!listResponse.ok) {
        throw await newRxFetchError(listResponse, {
            folderName: folderPath
        });
    }

    const listData = await listResponse.json();
    return listData.files || [];
}

export async function insertMultipartFile<T>(
    googleDriveOptions: GoogleDriveOptionsWithDefaults,
    folderId: string,
    filename: string,
    jsonData: T
) {
    const content = JSON.stringify(jsonData);

    const metadata = {
        name: filename,
        mimeType: 'application/json',
        parents: [folderId],
    };

    const postData = createMultipartBody(
        metadata,
        content
    );

    const res = await fetch(googleDriveOptions.apiEndpoint + "/upload/drive/v3/files?uploadType=multipart", {
        method: 'POST',
        headers: {
            Authorization: `Bearer ${googleDriveOptions.authToken}`,
            'Content-Type': 'multipart/related; boundary="' + postData.boundary + '"'
        },
        body: postData.body
    });
    if (!res.ok) {
        throw await newRxFetchError(res);
    }
}

export function createMultipartBody(
    metadata: Record<string, unknown>,
    content: string
) {
    const multipartBoundary = '-------1337-use-RxDB-7355608-' + Math.random().toString(16).slice(2);
    const delimiter = '\r\n--' + multipartBoundary + '\r\n';
    const closeDelim = '\r\n--' + multipartBoundary + '--';
    const body = delimiter +
        'Content-Type: application/json\r\n\r\n' +
        JSON.stringify(metadata) +
        delimiter +
        'Content-Type: application/json\r\n\r\n' +
        content +
        closeDelim;
    return { body, boundary: multipartBoundary };
};


export async function listFilesInFolder(
    googleDriveOptions: GoogleDriveOptionsWithDefaults,
    folderId: string
): Promise<DriveFileMetadata[]> {

    const q = `'${folderId}' in parents and trashed = false`;

    const params = new URLSearchParams({
        q,
        pageSize: "1000", // max allowed
        fields: "files(id,name,mimeType,parents,modifiedTime,size)",
        supportsAllDrives: "true",
        includeItemsFromAllDrives: "true",
    });
    applyDriveSpace(googleDriveOptions, params);

    const url =
        googleDriveOptions.apiEndpoint +
        "/drive/v3/files?" +
        params.toString();

    const res = await fetch(url, {
        headers: {
            Authorization: `Bearer ${googleDriveOptions.authToken}`,
        },
    });

    if (!res.ok) {
        const text = await res.text().catch(() => "");
        throw new Error(`files.list failed: ${res.status} ${text}`);
    }

    const data = await res.json();
    return data.files ?? [];
}