import type webpack from 'webpack'
import fs from 'fs'
import path from 'path'
import { imageExtMimeTypeMap } from '../../../lib/mime-type'
import { getLoaderModuleNamedExports } from './utils'
import { installBindings } from '../../swc/install-bindings'

function errorOnBadHandler(resourcePath: string) {
  return `
  if (typeof handler !== 'function') {
    throw new Error('Default export is missing in ${JSON.stringify(
      resourcePath
    )}')
  }
  `
}

/* re-export the userland route configs */
async function createReExportsCode(
  resourcePath: string,
  loaderContext: webpack.LoaderContext<any>
) {
  const exportNames = await getLoaderModuleNamedExports(
    resourcePath,
    loaderContext
  )
  // Re-export configs but avoid conflicted exports
  const reExportNames = exportNames.filter(
    (name) =>
      name !== 'default' &&
      name !== 'generateSitemaps' &&
      name !== 'dynamicParams'
  )

  return reExportNames.length > 0
    ? `export { ${reExportNames.join(', ')} } from ${JSON.stringify(
        resourcePath
      )}\n`
    : ''
}

const CACHE_HEADERS = {
  NO_CACHE: 'no-cache, no-store',
  REVALIDATE: 'public, max-age=0, must-revalidate',
}

export type MetadataRouteLoaderOptions = {
  // Using separate argument to avoid json being parsed and hit error
  // x-ref: https://github.com/vercel/next.js/pull/62615
  filePath: string
  isDynamicRouteExtension: '1' | '0'
}

export function getFilenameAndExtension(resourcePath: string) {
  const filename = path.basename(resourcePath)
  const [name, ext] = filename.split('.', 2)
  return {
    name,
    ext,
  }
}

function getContentType(resourcePath: string) {
  let { name, ext } = getFilenameAndExtension(resourcePath)
  if (ext === 'jpg') ext = 'jpeg'

  if (name === 'favicon' && ext === 'ico') return 'image/x-icon'
  if (name === 'sitemap') return 'application/xml'
  if (name === 'robots') return 'text/plain'
  if (name === 'manifest') return 'application/manifest+json'

  if (ext === 'png' || ext === 'jpeg' || ext === 'ico' || ext === 'svg') {
    return imageExtMimeTypeMap[ext]
  }
  return 'text/plain'
}

async function getStaticAssetRouteCode(
  resourcePath: string,
  fileBaseName: string
) {
  const cache =
    process.env.NODE_ENV !== 'production'
      ? CACHE_HEADERS.NO_CACHE
      : CACHE_HEADERS.REVALIDATE

  const isTwitter = fileBaseName === 'twitter-image'
  const isOpenGraph = fileBaseName === 'opengraph-image'
  // Twitter image file size limit is 5MB.
  // General Open Graph image file size limit is 8MB.
  // x-ref: https://developer.x.com/en/docs/x-for-websites/cards/overview/summary
  // x-ref(facebook): https://developers.facebook.com/docs/sharing/webmasters/images
  const fileSizeLimit = isTwitter ? 5 : 8
  const imgName = isTwitter ? 'Twitter' : 'Open Graph'

  const code = `\
/* static asset route */
import { NextResponse } from 'next/server'

const contentType = ${JSON.stringify(getContentType(resourcePath))}
const buffer = Buffer.from(${JSON.stringify(
    (await fs.promises.readFile(resourcePath)).toString('base64')
  )}, 'base64'
  )

if (${isTwitter || isOpenGraph}) {
  const fileSizeInMB = buffer.byteLength / 1024 / 1024
  if (fileSizeInMB > ${fileSizeLimit}) {
    throw new Error('File size for ${imgName} image ${JSON.stringify(resourcePath)} exceeds ${fileSizeLimit}MB. ' +
    \`(Current: \${fileSizeInMB.toFixed(2)}MB)\n\` +
    'Read more: https://nextjs.org/docs/app/api-reference/file-conventions/metadata/opengraph-image#image-files-jpg-png-gif'
    )
  }
}

export function GET() {
  return new NextResponse(buffer, {
    headers: {
      'Content-Type': contentType,
      'Cache-Control': ${JSON.stringify(cache)},
    },
  })
}

export const dynamic = 'force-static'
`
  return code
}

async function getDynamicTextRouteCode(
  resourcePath: string,
  loaderContext: webpack.LoaderContext<any>
) {
  return `\
/* dynamic asset route */
import { NextResponse } from 'next/server'
import handler from ${JSON.stringify(resourcePath)}
import { resolveRouteData } from 'next/dist/build/webpack/loaders/metadata/resolve-route-data'

const contentType = ${JSON.stringify(getContentType(resourcePath))}
const fileType = ${JSON.stringify(getFilenameAndExtension(resourcePath).name)}

${errorOnBadHandler(resourcePath)}
${await createReExportsCode(resourcePath, loaderContext)}

export async function GET() {
  const data = await handler()
  const content = resolveRouteData(data, fileType)

  return new NextResponse(content, {
    headers: {
      'Content-Type': contentType,
      'Cache-Control': ${JSON.stringify(CACHE_HEADERS.REVALIDATE)},
    },
  })
}
`
}

async function getDynamicImageRouteCode(
  resourcePath: string,
  loaderContext: webpack.LoaderContext<any>
) {
  return `\
/* dynamic image route with generateImageMetadata */
import { NextResponse } from 'next/server'
import { default as handler, generateImageMetadata } from ${JSON.stringify(resourcePath)}

${errorOnBadHandler(resourcePath)}
${await createReExportsCode(resourcePath, loaderContext)}

export async function GET(_, ctx) {
  const paramsPromise = ctx.params
  const idPromise = paramsPromise.then(params => params?.__metadata_id__)
  const restParamsPromise = paramsPromise.then(params => {
    if (!params) return undefined
    const { __metadata_id__, ...rest } = params
    return rest
  })

  const restParams = await restParamsPromise
  const __metadata_id__ = await idPromise
  const imageMetadata = await generateImageMetadata({ params: restParams })
  const id = imageMetadata.find((item) => {
    if (item?.id == null) {
      throw new Error('id property is required for every item returned from generateImageMetadata')
    }

    return item.id.toString() === __metadata_id__
  })?.id

  if (id == null) {
    return new NextResponse('Not Found', {
      status: 404,
    })
  }

  return handler({ params: restParamsPromise, id: idPromise })
}

export async function generateStaticParams({ params }) {
  const imageMetadata = await generateImageMetadata({ params })
  const staticParams = []

  for (const item of imageMetadata) {
    if (item?.id == null) {
      throw new Error('id property is required for every item returned from generateImageMetadata')
    }
    staticParams.push({ __metadata_id__: item.id.toString() })
  }
  return staticParams
}
`
}

async function getSingleImageRouteCode(
  resourcePath: string,
  loaderContext: webpack.LoaderContext<any>
) {
  return `\
/* dynamic image route without generateImageMetadata */
import { NextResponse } from 'next/server'
import { default as handler } from ${JSON.stringify(resourcePath)}

${errorOnBadHandler(resourcePath)}
${await createReExportsCode(resourcePath, loaderContext)}

export async function GET(_, ctx) {
  return handler({ params: ctx.params })
}
`
}

// <metadata-image>/[id]/route.js
async function getImageRouteCode(
  resourcePath: string,
  loaderContext: webpack.LoaderContext<any>
) {
  const exportNames = await getLoaderModuleNamedExports(
    resourcePath,
    loaderContext
  )

  const hasGenerateParamsExport = exportNames.includes('generateImageMetadata')

  if (hasGenerateParamsExport) {
    return getDynamicImageRouteCode(resourcePath, loaderContext)
  } else {
    return getSingleImageRouteCode(resourcePath, loaderContext)
  }
}

async function getSingleSitemapRouteCode(
  resourcePath: string,
  loaderContext: webpack.LoaderContext<any>
) {
  return `\
/* single sitemap route */
import { NextResponse } from 'next/server'
import { default as handler } from ${JSON.stringify(resourcePath)}
import { resolveRouteData } from 'next/dist/build/webpack/loaders/metadata/resolve-route-data'

const contentType = ${JSON.stringify(getContentType(resourcePath))}
const fileType = ${JSON.stringify(getFilenameAndExtension(resourcePath).name)}

${errorOnBadHandler(resourcePath)}
${await createReExportsCode(resourcePath, loaderContext)}

export async function GET() {
  const data = await handler()
  const content = resolveRouteData(data, fileType)

  return new NextResponse(content, {
    headers: {
      'Content-Type': contentType,
      'Cache-Control': ${JSON.stringify(CACHE_HEADERS.REVALIDATE)},
    },
  })
}
`
}

async function getDynamicSitemapRouteCode(
  resourcePath: string,
  loaderContext: webpack.LoaderContext<any>
) {
  const code = `\
/* dynamic sitemap route with generateSitemaps */
import { NextResponse } from 'next/server'
import { default as handler, generateSitemaps } from ${JSON.stringify(resourcePath)}
import { resolveRouteData } from 'next/dist/build/webpack/loaders/metadata/resolve-route-data'

const contentType = ${JSON.stringify(getContentType(resourcePath))}
const fileType = ${JSON.stringify(getFilenameAndExtension(resourcePath).name)}

${errorOnBadHandler(resourcePath)}
${await createReExportsCode(resourcePath, loaderContext)}

export async function GET(_, ctx) {
  const paramsPromise = ctx.params
  const idPromise = paramsPromise.then(params => params?.__metadata_id__)

  const id = await idPromise
  const hasXmlExtension = id ? id.endsWith('.xml') : false
  const sitemaps = await generateSitemaps()
  let foundId
  for (const item of sitemaps) {
    if (item?.id == null) {
      throw new Error('id property is required for every item returned from generateSitemaps')
    }

    const baseId = id && hasXmlExtension ? id.slice(0, -4) : undefined
    if (item.id.toString() === baseId) {
      foundId = item.id
    }
  }
  if (foundId == null) {
    return new NextResponse('Not Found', {
      status: 404,
    })
  }

  const targetIdPromise = idPromise.then(id => {
    const hasXmlExtension = id ? id.endsWith('.xml') : false
    return id && hasXmlExtension ? id.slice(0, -4) : undefined
  })
  const data = await handler({ id: targetIdPromise })
  const content = resolveRouteData(data, fileType)

  return new NextResponse(content, {
    headers: {
      'Content-Type': contentType,
      'Cache-Control': ${JSON.stringify(CACHE_HEADERS.REVALIDATE)},
    },
  })
}

export async function generateStaticParams() {
  const sitemaps = await generateSitemaps()
  const params = []

  for (const item of sitemaps) {
    if (item?.id == null) {
      throw new Error('id property is required for every item returned from generateSitemaps')
    }
    params.push({ __metadata_id__: item.id.toString() + '.xml' })
  }
  return params
}
`
  return code
}

// <metadata-sitemap>/[id]/route.js
async function getSitemapRouteCode(
  resourcePath: string,
  loaderContext: webpack.LoaderContext<any>
) {
  const exportNames = await getLoaderModuleNamedExports(
    resourcePath,
    loaderContext
  )

  const hasGenerateSitemaps = exportNames.includes('generateSitemaps')

  if (hasGenerateSitemaps) {
    return getDynamicSitemapRouteCode(resourcePath, loaderContext)
  } else {
    return getSingleSitemapRouteCode(resourcePath, loaderContext)
  }
}

// When it's static route, it could be favicon.ico, sitemap.xml, robots.txt etc.
// TODO-METADATA: improve the cache control strategy
const nextMetadataRouterLoader: webpack.LoaderDefinitionFunction<MetadataRouteLoaderOptions> =
  async function () {
    // Install bindings early so they are definitely available to the loader.
    // When run by webpack in next this is already done with correct configuration so this is a no-op.
    // In turbopack loaders are run in a subprocess so it may or may not be done.
    await installBindings()
    const { isDynamicRouteExtension, filePath } = this.getOptions()
    const { name: fileBaseName } = getFilenameAndExtension(filePath)
    this.addDependency(filePath)

    let code = ''
    if (isDynamicRouteExtension === '1') {
      if (fileBaseName === 'robots' || fileBaseName === 'manifest') {
        code = await getDynamicTextRouteCode(filePath, this)
      } else if (fileBaseName === 'sitemap') {
        code = await getSitemapRouteCode(filePath, this)
      } else {
        code = await getImageRouteCode(filePath, this)
      }
    } else {
      code = await getStaticAssetRouteCode(filePath, fileBaseName)
    }

    return code
  }

export default nextMetadataRouterLoader