package fbhttp

import (
    "strings"
    "unicode"
    id3v2 "github.com/bogem/id3v2/v2"
)

// clearID3v2Frames removes specific ID3v2 frames from an MP3 file.
// frames: list of standard frame IDs (e.g., TIT2, TPE1, TPE2, TRCK, TPOS, TCON, TDRC, COMM, USLT)
// txxxDescs: list of UserDefinedText (TXXX) descriptions to remove (e.g., "Artists", "AlbumArtists").
func clearID3v2Frames(path string, frames []string, txxxDescs []string, removeNumericEmpty bool) error {
    tag, err := id3v2.Open(path, id3v2.Options{Parse: true})
    if err != nil {
        return err
    }
    defer tag.Close()

    // Delete standard frames
    for _, id := range frames {
        tag.DeleteFrames(id)
    }

    // Delete matching TXXX frames by description (preserve others)
    if len(txxxDescs) > 0 {
        fs := tag.GetFrames("TXXX")
        keep := []id3v2.UserDefinedTextFrame{}
        for _, f := range fs {
            udf, ok := f.(id3v2.UserDefinedTextFrame)
            if !ok {
                continue
            }
            remove := false
            for _, d := range txxxDescs {
                if strings.EqualFold(udf.Description, d) {
                    remove = true
                    break
                }
            }
            if !remove && removeNumericEmpty {
                desc := strings.TrimSpace(udf.Description)
                if desc == "" {
                    remove = true
                } else {
                    // numeric-only descriptions like "0", "1", "2"
                    allDigits := true
                    for _, r := range desc {
                        if !unicode.IsDigit(r) {
                            allDigits = false
                            break
                        }
                    }
                    if allDigits {
                        remove = true
                    }
                }
            }
            if !remove {
                keep = append(keep, udf)
            }
        }
        // Remove all TXXX frames, then re-add the ones we keep
        tag.DeleteFrames("TXXX")
        for _, udf := range keep {
            tag.AddFrame("TXXX", udf)
        }
    }

    return tag.Save()
}

// cleanupNumericEmptyTXXX removes any TXXX frames whose descriptions are empty
// or purely numeric (e.g., "0", "1", "2"…), which are common artifacts.
func cleanupNumericEmptyTXXX(path string) error {
    tag, err := id3v2.Open(path, id3v2.Options{Parse: true})
    if err != nil {
        return err
    }
    defer tag.Close()

    fs := tag.GetFrames("TXXX")
    keep := []id3v2.UserDefinedTextFrame{}
    for _, f := range fs {
        udf, ok := f.(id3v2.UserDefinedTextFrame)
        if !ok {
            continue
        }
        desc := strings.TrimSpace(udf.Description)
        remove := false
        if desc == "" {
            remove = true
        } else {
            allDigits := true
            for _, r := range desc {
                if !unicode.IsDigit(r) {
                    allDigits = false
                    break
                }
            }
            if allDigits {
                remove = true
            }
        }
        if !remove {
            keep = append(keep, udf)
        }
    }
    // If nothing to change, return early
    if len(keep) == len(fs) {
        return nil
    }
    tag.DeleteFrames("TXXX")
    for _, udf := range keep {
        tag.AddFrame("TXXX", udf)
    }
    return tag.Save()
}