package service

import (
	"fmt"
	"strconv"
	"strings"

	"vidarchive/internal/models"
	"vidarchive/internal/repository"
)

// PresetService adds yt-dlp argument building on top of preset storage. The
// repository is embedded rather than wrapped in forwarding methods: every one of
// its methods (Save, GetByID, GetAll, GetDefault, Delete) is part of this
// service's contract anyway.
type PresetService struct {
	*repository.PresetRepository
}

func NewPresetService(repo *repository.PresetRepository) *PresetService {
	return &PresetService{PresetRepository: repo}
}

func (s *PresetService) BuildArgs(p *models.Preset, formatOverride, customFlags string) []string {
	var args []string

	// Format selection
	if formatOverride != "" {
		args = append(args, "-f", formatOverride)
	} else if p.FormatMode == "custom" && p.CustomFormat != "" {
		args = append(args, "-f", p.CustomFormat)
	} else if p.FormatMode == "preset" && p.Format != "" {
		if p.Quality != "" {
			args = append(args, "-f", applyHeightCap(p.Format, p.Quality))
		} else {
			args = append(args, "-f", p.Format)
		}
	}
	// If FormatMode is "default" or empty, don't pass -f (let yt-dlp choose)

	// Audio extraction
	if p.ExtractAudio {
		args = append(args, "--extract-audio")
		if p.AudioFormat != "" {
			args = append(args, "--audio-format", p.AudioFormat)
		}
	}

	// Subtitles
	if p.EmbedSubs {
		args = append(args, "--embed-subs")
		if p.SubLangs != "" {
			args = append(args, "--sub-langs", p.SubLangs)
		}
	}

	// Thumbnail
	if p.EmbedThumbnail {
		args = append(args, "--embed-thumbnail")
	}

	// Metadata
	if p.EmbedMetadata {
		args = append(args, "--embed-metadata")
	}

	// Info JSON and comments. Comments are stored in the info JSON sidecar, so
	// enabling comment collection implicitly enables sidecar writing.
	if p.WriteInfoJSON || p.WriteComments {
		args = append(args, "--write-info-json")
	}
	if p.WriteComments {
		args = append(args, "--write-comments")
	}
	var commentArgs []string
	commentSort := strings.TrimSpace(p.CommentSort)
	if commentSort != "" {
		commentArgs = append(commentArgs, "comment_sort="+commentSort)
	}
	if p.MaxComments > 0 {
		commentArgs = append(commentArgs, "max_comments="+strconv.Itoa(p.MaxComments))
	}
	// yt-dlp's syntax is IE_KEY:ARG1=VAL1,VAL2;ARG2=VAL: arguments are separated
	// by ";", only the values of one argument by ",". Passing --extractor-args
	// twice for the same key makes the second replace the first, so all youtube
	// arguments must go into a single flag.
	extra := strings.TrimSpace(p.CommentExtractorArgs)
	if rest, ok := cutYoutubePrefix(extra); ok {
		if rest != "" {
			commentArgs = append(commentArgs, rest)
		}
		extra = ""
	}
	if len(commentArgs) > 0 {
		args = append(args, "--extractor-args", "youtube:"+strings.Join(commentArgs, ";"))
	}
	if extra != "" {
		args = append(args, "--extractor-args", extra)
	}

	// Custom flags
	args = append(args, splitCustomFlags(p.CustomFlags)...)
	args = append(args, splitCustomFlags(customFlags)...)

	return args
}

// cutYoutubePrefix strips a leading "youtube:" (any case) from extractor args.
// The bool reports whether the value targeted the youtube extractor at all.
func cutYoutubePrefix(s string) (string, bool) {
	if len(s) < len("youtube:") || !strings.EqualFold(s[:len("youtube:")], "youtube:") {
		return s, false
	}
	return strings.TrimSpace(s[len("youtube:"):]), true
}

// splitCustomFlags splits a custom-flags string into arguments. BuildArgs cannot
// report an error, so malformed quoting falls back to whitespace splitting. The
// download path already rejected such input in checkReservedFlags, so only the
// EffectiveFlags display can reach the fallback.
func splitCustomFlags(s string) []string {
	if strings.TrimSpace(s) == "" {
		return nil
	}
	fields, err := splitFlags(s)
	if err != nil {
		return strings.Fields(s)
	}
	return fields
}

// applyHeightCap adds a max-height filter to a format selector. For a combined
// "video+audio" selector it binds the filter to the video stream only (e.g.
// "bestvideo[height<=720]+bestaudio"), since applying it to the whole expression
// would wrongly constrain the audio selector. It always appends an unfiltered
// fallback so a missing capped variant still resolves.
func applyHeightCap(format, maxHeight string) string {
	parts := strings.Split(format, "+")
	parts[0] = fmt.Sprintf("%s[height<=%s]", parts[0], maxHeight)
	return strings.Join(parts, "+") + "/" + format
}

func (s *PresetService) EffectiveFlags(p *models.Preset, formatOverride, customFlags string) string {
	args := s.BuildArgs(p, formatOverride, customFlags)
	return strings.Join(args, " ")
}