package task

import (
	"bufio"
	"bytes"
	"context"
	"crypto/md5"
	"fmt"
	"io"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"slices"
	"sync"
	"time"

	"git.lastassault.de/speatzle/morffix/config"
	"git.lastassault.de/speatzle/morffix/constants"
	"git.lastassault.de/speatzle/morffix/task/log"
	"git.lastassault.de/speatzle/morffix/types"
)

type countReader struct {
	io.Reader
	n int
}

func (w *countReader) Read(p []byte) (int, error) {
	n, err := w.Reader.Read(p)
	w.n += n
	return n, err
}

// dropCR drops a terminal \r from the data.
func dropCR(data []byte) []byte {
	if len(data) > 0 && data[len(data)-1] == '\r' {
		return data[0 : len(data)-1]
	}
	return data
}

func scanLines(data []byte, atEOF bool) (advance int, token []byte, err error) {
	if atEOF && len(data) == 0 {
		return 0, nil, nil
	}
	if i := bytes.IndexByte(data, '\n'); i >= 0 {
		// We have a full newline-terminated line.
		return i + 1, dropCR(data[0:i]), nil
	}
	if i := bytes.IndexByte(data, '\r'); i >= 0 {
		// We have a return line.
		return i + 1, dropCR(data[0:i]), nil
	}
	// If we're at EOF, we have a final, non-terminated line. Return it.
	if atEOF {
		return len(data), dropCR(data), nil
	}
	// Request more data.
	return 0, nil, nil
}

func RunHealthCheck(conf config.Config, t *types.Task, data types.HealthCheckData) {
	ctx := context.TODO()
	l := log.GetTaskLogger(t)

	// TODO Figure out how to get correct file ending
	path := filepath.Join(conf.Worker.TempDir, fmt.Sprintf("%v-%v.mkv", t.ID, t.FileID))

	// Set ffmpeg input path
	if len(data.Command.InputFiles) == 0 {
		l.ErrorContext(ctx, "FFmpeg Command has no input files")
		return
	}

	data.Command.InputFiles[0].Path = path

	// TODO cleanup file when done
	defer func() {
		err := os.Remove(path)
		if err != nil {
			l.ErrorContext(ctx, "Removing File", "err", err, "path", path)
		} else {
			l.InfoContext(ctx, "File Removed Succesfully", "path", path)
		}
	}()

	l.InfoContext(ctx, "Starting File Download", "task_id", t.ID, "file_id", t.FileID, "path", path, "md5", t.FileMD5)

	err := func() error {
		out, err := os.Create(path)
		if err != nil {
			return fmt.Errorf("Creating File: %w", err)
		}
		defer out.Close()

		req, err := http.NewRequest(http.MethodGet, fmt.Sprintf("%v/files/%v", conf.Worker.Address, t.FileID), nil)
		if err != nil {
			return fmt.Errorf("New Request: %w", err)
		}

		req.Close = true

		var client = &http.Client{
			Transport: &http.Transport{},
		}
		resp, err := client.Do(req)
		if err != nil {
			return fmt.Errorf("Getting File: %w", err)
		}

		if resp.StatusCode != http.StatusOK {
			return fmt.Errorf("Got HTTP Status Code: %v", resp.StatusCode)
		}

		req.Close = true

		// TODO Log at interval logs read

		// Calculate hash and write file at the same time
		hash := md5.New()
		tr := io.TeeReader(resp.Body, hash)

		cr := &countReader{Reader: tr}

		stopProgress := make(chan bool, 1)

		go func() {
			tik := time.NewTicker(time.Second)

			lastCount := 0

			for {
				select {
				case <-tik.C:
					speed := cr.n - lastCount
					l.InfoContext(ctx, "Download Progress", "bytes", cr.n, "lastCount", lastCount, "length", resp.ContentLength, "speed", speed)
					lastCount = cr.n
				case <-stopProgress:
					tik.Stop()
				}

			}
		}()

		defer func() {
			stopProgress <- true
		}()

		defer resp.Body.Close()
		n, err := io.Copy(out, cr)
		if err != nil {
			return fmt.Errorf("Reading File: %w", err)
		}

		md5 := hash.Sum(nil)

		l.InfoContext(ctx, "Downloaded File", "bytes", n, "md5", md5)

		if slices.Compare[[]byte](md5, t.FileMD5) != 0 {
			return fmt.Errorf("Downloaded File does not match md5")
		}

		return nil
	}()

	if err != nil {
		l.ErrorContext(ctx, "File Download Failed", "err", err)
		return
	}

	l.InfoContext(ctx, "Running ffmpeg", "args", data.Command.GetArgs())
	cmd := exec.CommandContext(ctx, conf.Worker.FFmpegPath, data.Command.GetArgs()...)

	var wg sync.WaitGroup

	stdout, err := cmd.StdoutPipe()
	if err != nil {
		l.ErrorContext(ctx, "Error getting StdoutPipe", "err", err)
		return
	}

	wg.Add(1)
	outScanner := bufio.NewScanner(stdout)
	outScanner.Split(scanLines)
	go func() {
		for outScanner.Scan() {
			l.InfoContext(ctx, outScanner.Text())
		}
		wg.Done()
	}()

	stderr, err := cmd.StderrPipe()
	if err != nil {
		l.ErrorContext(ctx, "Error getting StderrPipe", "err", err)
		return
	}
	wg.Add(1)
	errScanner := bufio.NewScanner(stderr)
	errScanner.Split(scanLines)
	go func() {
		for errScanner.Scan() {
			l.InfoContext(ctx, errScanner.Text())
		}
		wg.Done()
	}()

	err = cmd.Start()
	if err != nil {
		l.ErrorContext(ctx, "Error Starting ffmpeg", "err", err)
		return
	}

	wg.Wait()

	err = cmd.Wait()
	if err != nil {
		l.ErrorContext(ctx, "Error Running ffmpeg", "err", err)
		return
	}

	l.InfoContext(ctx, "Task Success")
	t.Status = constants.TASK_STATUS_SUCCESS
}