import {FileMetadata, FileNotFoundError, Filesystem, Stat} from "./Filesystem"
import * as fs from "fs"
import * as path from "path"
import {UniversalPath} from "../path"
import * as rimraf from "rimraf"
import * as mkdirp from "mkdirp"

export interface LocalFilesystemConfig {
    baseDir: string
}

/**
 * A Filesystem implementation that stores files on the local disk.
 * @todo walk
 */
export class LocalFilesystem extends Filesystem {
    constructor(
        protected readonly baseConfig: LocalFilesystemConfig
    ) { super() }

    async open(): Promise<void> {
        // Make sure the base directory exists
        await mkdirp(this.baseConfig.baseDir)
        await mkdirp(this.storePath(''))
        await mkdirp(this.metadataPath(''))
    }

    public getPrefix(): string {
        return 'local://'
    }

    public async putLocalFile({localPath, storePath, ...args}: {localPath: string, storePath: string, mimeType?: string, tags?: string[], tag?: string}) {
        await fs.promises.copyFile(localPath, this.storePath(storePath))
        await fs.promises.writeFile(this.metadataPath(storePath), JSON.stringify({
            mimeType: args.mimeType,
            tags: this._normalizeTags(args.tag, args.tags),
        }))
    }

    public async getStoreFileAsTemp({ storePath }: {storePath: string}): Promise<UniversalPath> {
        const tempName = this.tempName()
        await fs.promises.copyFile(this.storePath(storePath), tempName)
        return new UniversalPath(tempName)
    }

    public getStoreFileAsStream(args: { storePath: string }): fs.ReadStream | Promise<fs.ReadStream> {
        return fs.createReadStream(this.storePath(args.storePath))
    }

    public putStoreFileAsStream(args: { storePath: string }): fs.WriteStream | Promise<fs.WriteStream> {
        return fs.createWriteStream(this.storePath(args.storePath))
    }

    public async getMetadata(storePath: string) {
        try {
            const json = (await fs.promises.readFile(this.metadataPath(storePath))).toString('utf-8')
            return JSON.parse(json)
        } catch (e) {
            return {
                tags: []
            }
        }
    }

    async setMetadata(storePath: string, meta: FileMetadata): Promise<void> {
        if ( !(await this.stat({storePath})).exists ) {
            throw new FileNotFoundError(storePath)
        }

        const metaPath = this.metadataPath(storePath)
        await fs.promises.writeFile(metaPath, JSON.stringify(meta))
    }

    public async stat(args: { storePath: string }): Promise<Stat> {
        try {
            const stat = await fs.promises.stat(this.storePath(args.storePath))
            const meta = await this.getMetadata(args.storePath)

            return {
                path: new UniversalPath(args.storePath, this),
                exists: true,
                sizeInBytes: stat.size,
                mimeType: meta.mimeType,
                tags: meta.tags,
                accessed: stat.atime,
                modified: stat.mtime,
                created: stat.ctime,
            }
        } catch (e) {
            if ( e?.code === 'ENOENT' ) {
                return {
                    path: new UniversalPath(args.storePath, this),
                    exists: false,
                    sizeInBytes: 0,
                    tags: []
                }
            }

            throw e
        }
    }

    public async touch(args: {storePath: string}): Promise<void> {
        return new Promise<void>((res, rej) => {
            const storePath = this.storePath(args.storePath)
            const time = new Date()
            fs.utimes(storePath, time, time, err => {
                if ( err ) {
                    fs.open(storePath, 'w', (err2, fd) => {
                        if ( err2 ) return rej(err2)
                        fs.close(fd, err3 => {
                            if ( err3 ) return rej(err3)
                            res()
                        })
                    })
                } else {
                    res()
                }
            })
        })
    }

    public async remove(args: { storePath: string; recursive?: boolean }): Promise<void> {
        if ( !args.recursive ) {
            await fs.promises.unlink(this.storePath(args.storePath))
            await fs.promises.unlink(this.metadataPath(args.storePath))
        } else {
            await new Promise<void>((res, rej) => {
                rimraf(this.storePath(args.storePath), err => {
                    if ( err ) return rej(err)
                    else {
                        fs.promises.unlink(this.metadataPath(args.storePath)).then(() => res()).catch(rej)
                    }
                })
            })
        }
    }

    public async mkdir(args: {storePath: string}): Promise<void> {
        await mkdirp(this.storePath(args.storePath))
    }

    /**
     * Given a relative path in the store, resolve it to an absolute path.
     * @param storePath
     * @protected
     */
    protected storePath(storePath: string): string {
        return path.resolve(this.baseConfig.baseDir, 'data', storePath)
    }

    /**
     * Given a relative path in the store, resolve it to an absolute path to the metadata JSON
     * file for that path.
     * @param storePath
     * @protected
     */
    protected metadataPath(storePath: string): string {
        return path.resolve(this.baseConfig.baseDir, 'meta', storePath + '.json')
    }
}