package ytdl

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"os/exec"
	"strings"

	"go.fifitido.net/ytdl-web/config"
	"go.fifitido.net/ytdl-web/pkg/ytdl/cache"
	"go.fifitido.net/ytdl-web/pkg/ytdl/metadata"
	"golang.org/x/exp/slog"
)

type Ytdl interface {
	GetMetadata(url string) (*metadata.Metadata, error)
	Download(w io.Writer, url, format string, index int) error
	Version() string
}

type ytdlImpl struct {
	cfg     *config.Config
	logger  *slog.Logger
	cache   cache.MetadataCache
	version string
}

func NewYtdl(cfg *config.Config, logger *slog.Logger, cache cache.MetadataCache) Ytdl {
	cmd := exec.Command(
		cfg.Ytdlp.BinaryPath,
		"--version",
	)
	var out bytes.Buffer
	cmd.Stdout = &out
	_ = cmd.Run()

	return &ytdlImpl{
		cfg:     cfg,
		logger:  logger.With(slog.String("module", "ytdl")),
		cache:   cache,
		version: strings.TrimSpace(out.String()),
	}
}

func buildBrowserCookieString(browser, keyring, profile, container string) string {
	var sb strings.Builder
	sb.WriteString(browser)

	if keyring != "" {
		sb.WriteByte('+')
		sb.WriteString(keyring)
	}

	if profile != "" {
		sb.WriteByte(':')
		sb.WriteString(profile)
	}

	if container != "" {
		sb.WriteByte(':')
		sb.WriteByte(':')
		sb.WriteString(container)
	}

	return sb.String()
}

func (y *ytdlImpl) appendCookieArgs(args []string) []string {
	if y.cfg.Cookies.Enabled {
		if y.cfg.Cookies.FromBrowser.Browser != "" {
			args = append(args, "--cookies-from-browser", buildBrowserCookieString(
				y.cfg.Cookies.FromBrowser.Browser,
				y.cfg.Cookies.FromBrowser.Keyring,
				y.cfg.Cookies.FromBrowser.Profile,
				y.cfg.Cookies.FromBrowser.Container,
			))
		} else {
			args = append(args, "--cookies", y.cfg.Cookies.FilePath)
		}
	}

	return args
}

func (y *ytdlImpl) Version() string {
	return y.version
}

// GetMetadata implements Ytdl
func (y *ytdlImpl) GetMetadata(url string) (*metadata.Metadata, error) {
	meta, err := y.cache.Get(url)
	if err == nil {
		return meta, nil
	}

	args := []string{
		url,
		"--dump-single-json",
	}

	args = y.appendCookieArgs(args)

	cmd := exec.Command(y.cfg.Ytdlp.BinaryPath, args...)

	out, err := cmd.Output()
	if err != nil {
		attrs := []any{
			slog.String("url", url),
			slog.String("error", err.Error()),
		}

		y.logger.Error("failed to get metadata", attrs...)
		return nil, err
	}

	meta = &metadata.Metadata{}
	if err := json.Unmarshal(out, meta); err != nil {
		y.logger.Error("failed to unmarshal metadata", slog.String("url", url), slog.String("error", err.Error()))
		return nil, err
	}

	if err := y.cache.Set(url, meta, y.cfg.Cache.TTL); err != nil {
		y.logger.Warn("failed to cache metadata", slog.String("url", url), slog.String("error", err.Error()))
	}

	return meta, nil
}

// Download implements Ytdl
func (y *ytdlImpl) Download(w io.Writer, url, format string, index int) error {
	args := []string{
		url,
		"--format", format,
		"--output", "-",
	}

	if index >= 0 {
		args = append(args, "--playlist-ites", fmt.Sprint(index+1))
	}

	args = y.appendCookieArgs(args)

	metadata, err := y.cache.Get(url)
	if err == nil {
		args = append(args, "--load-info-json", "-")
	}

	cmd := exec.Command(y.cfg.Ytdlp.BinaryPath, args...)
	cmd.Stdout = w

	if err == nil {
		json, err := json.Marshal(metadata)
		if err != nil {
			return err
		}

		cmd.Stdin = bytes.NewReader(json)
	}

	if err := cmd.Run(); err != nil {
		y.logger.Error("failed to download", slog.String("url", url), slog.String("error", err.Error()))
		return err
	}

	return nil
}