import http from 'http'
import { measure } from 'measurement-protocol'
import matchRoute from 'my-way'

import { serveBadgeNext } from './serve-badge-next'
import serveDoc from './serve-doc'
import sentry from './sentry'

import type { NextApiRequest, NextApiResponse } from 'next'
import type { BadgenParams } from './types'

export type PathArgs = NonNullable<ReturnType<typeof matchRoute>>

export interface BadgenServeConfig {
    title: string;
    help?: string;
    examples: { [url: string]: string };
    handlers: { [pattern: string]: (pathArgs: PathArgs) => Promise<BadgenParams> };
  }

export function createBadgenHandler (badgenServerConfig: BadgenServeConfig) {
  const { handlers } = badgenServerConfig

  async function nextHandler (req: NextApiRequest, res: NextApiResponse) {
    let { pathname } = new URL(req.url || '/', `http://${req.headers.host}`)

    if (pathname === '/favicon.ico') {
      return res.end()
    }

    // Match badge handlers
    let matchedArgs: PathArgs | null = null
    const matchedScheme = Object.keys(handlers).find(scheme => {
      return matchedArgs = matchRoute(scheme, decodeURI(pathname))
    })

    // Invoke badge handler
    if (matchedArgs !== null && matchedScheme !== undefined) {
      return await handlers[matchedScheme](matchedArgs).then(params => {
        return serveBadgeNext(req, res, { params })
      }).catch(e => {
        return onBadgeHandlerError(e, req, res)
      })
    }

    if (matchRoute('/:name', pathname)) {
      return serveDoc(badgenServerConfig)(req, res)
      // return res.send('TODO: serve doc page')
    }

    return res.status(404).end()
  }

  return nextHandler
}

function onBadgeHandlerError (err: Error, req: NextApiRequest, res: NextApiResponse) {
  // Send user friendly response
  res.status(500).setHeader('error-message', err.message)
  return serveBadgeNext(req, res, {
    code: 200,
    params: {
      subject: 'error',
      status: '',
      color: 'red'
    }
  })
}

const { TRACKING_GA, NOW_REGION } = process.env
const tracker = TRACKING_GA && measure(TRACKING_GA).setCustomDimensions([NOW_REGION || 'unknown'])

async function measurementLogInvocation (host: string, urlPath: string) {
  tracker && tracker.pageview({ host, path: urlPath}).send()
}

async function measurementLogError (category: string, action: string, label?: string, value?: number) {
  tracker && tracker.event(category, action, label, value).send()
}

function getBadgeStyle (req: http.IncomingMessage): string | undefined {
  const host = req.headers['x-forwarded-host']?.toString() ?? req.headers.host ?? ''
  return host.startsWith('flat') ? 'flat' : undefined
}

function simpleDecode (str: string): string {
  return String(str).replace(/%2F/g, '/')
}