package utils

import (
	"strconv"
	"strings"

	"bookhoard/internal/database"

	"github.com/jackc/pgx/v5/pgtype"
)

// Per-field user-override tracking for media item metadata.
//
// metadata_overrides is a TEXT[] column on media_items holding the names of
// columns the user has customized via the metadata editor. Library scans and
// per-book rescans MUST preserve those columns (applyMetadataOverrides);
// only the reset-to-scanned-defaults action clears the set.

const (
	OverrideTitle            = "title"
	OverrideAuthor           = "author"
	OverrideISBN             = "isbn"
	OverrideDescription      = "description"
	OverrideCoverImagePath   = "cover_image_path"
	OverrideSeries           = "series"
	OverrideSeriesNumber     = "series_number"
	OverrideTags             = "tags"
	OverrideAsin             = "asin"
	OverrideDatePublished    = "date_published"
	OverridePublisher        = "publisher"
	OverrideContributors     = "contributors"
	OverrideLanguage         = "language"
	OverrideEdition          = "edition"
	OverridePageCount        = "page_count"
	OverrideGenre            = "genre"
	OverrideCopyrightYear    = "copyright_year"
	OverrideGoodreadsID      = "goodreads_id"
	OverrideOpenlibraryID    = "openlibrary_id"
	OverrideGoogleBooksID    = "google_books_id"
	OverrideMangaType        = "manga_type"
	OverrideReadingDirection = "reading_direction"
	OverrideSeriesCount      = "series_count"
	OverrideVolume           = "volume"
	OverrideImprint          = "imprint"
	OverrideAgeRating        = "age_rating"
	OverrideWebURL           = "web_url"
	OverrideMetadataNotes    = "metadata_notes"
	OverrideCommunityRating  = "community_rating"
	OverrideStoryArc         = "story_arc"
	OverrideIsBlackAndWhite  = "is_black_and_white"
	OverrideAlternateInfo    = "alternate_info"
	OverrideScanInformation  = "scan_information"
	OverrideSummary          = "summary"
)

// hasOverride reports whether key is in the override set.
func hasOverride(overrides []string, key string) bool {
	for _, k := range overrides {
		if k == key {
			return true
		}
	}
	return false
}

// MergeOverrides unions existing and added, preserving order and dropping
// duplicates. Returns a non-nil slice so it always satisfies NOT NULL columns.
func MergeOverrides(existing []string, added ...string) []string {
	seen := make(map[string]bool, len(existing)+len(added))
	merged := make([]string, 0, len(existing)+len(added))
	for _, k := range existing {
		if k != "" && !seen[k] {
			seen[k] = true
			merged = append(merged, k)
		}
	}
	for _, k := range added {
		if k != "" && !seen[k] {
			seen[k] = true
			merged = append(merged, k)
		}
	}
	return merged
}

// Normalizers turn nullable column values into comparable strings so that
// "unset" (invalid/zero) forms compare equal regardless of which side they
// come from.

func normText(t pgtype.Text) string {
	if !t.Valid {
		return ""
	}
	return t.String
}

func normInt(i pgtype.Int4) string {
	if !i.Valid {
		return ""
	}
	return strconv.FormatInt(int64(i.Int32), 10)
}

func normFloat(f pgtype.Float8) string {
	if !f.Valid {
		return ""
	}
	return strconv.FormatFloat(f.Float64, 'g', -1, 64)
}

func normBool(b pgtype.Bool) string {
	if !b.Valid {
		return ""
	}
	return strconv.FormatBool(b.Bool)
}

func normDate(d pgtype.Date) string {
	if !d.Valid {
		return ""
	}
	return d.Time.Format("2006-01-02")
}

func normStringSlice(s []string) string {
	if len(s) == 0 {
		return ""
	}
	return strings.Join(s, "\x1f")
}

func normBytes(b []byte) string {
	if len(b) == 0 {
		return ""
	}
	return string(b)
}

// detectMetadataOverridesDiff returns the keys whose value in params differs
// from the existing row. Used by the metadata editor save path to grow the
// override set with exactly the fields the user changed.
func detectMetadataOverridesDiff(params database.UpdateMediaItemParams, existing database.MediaItems) []string {
	var changed []string
	add := func(key string, differs bool) {
		if differs {
			changed = append(changed, key)
		}
	}

	add(OverrideTitle, params.Title != existing.Title)
	add(OverrideAuthor, normText(params.Author) != normText(existing.Author))
	add(OverrideISBN, normText(params.Isbn) != normText(existing.Isbn))
	add(OverrideDescription, normText(params.Description) != normText(existing.Description))
	add(OverrideSeries, normText(params.Series) != normText(existing.Series))
	add(OverrideSeriesNumber, normInt(params.SeriesNumber) != normInt(existing.SeriesNumber))
	add(OverrideTags, normStringSlice(params.Tags) != normStringSlice(existing.Tags))
	add(OverrideAsin, normText(params.Asin) != normText(existing.Asin))
	add(OverrideDatePublished, normDate(params.DatePublished) != normDate(existing.DatePublished))
	add(OverridePublisher, normText(params.Publisher) != normText(existing.Publisher))
	add(OverrideContributors, normStringSlice(params.Contributors) != normStringSlice(existing.Contributors))
	add(OverrideLanguage, normText(params.Language) != normText(existing.Language))
	add(OverrideEdition, normText(params.Edition) != normText(existing.Edition))
	add(OverridePageCount, normInt(params.PageCount) != normInt(existing.PageCount))
	add(OverrideGenre, normText(params.Genre) != normText(existing.Genre))
	add(OverrideCopyrightYear, normInt(params.CopyrightYear) != normInt(existing.CopyrightYear))
	add(OverrideGoodreadsID, normText(params.GoodreadsID) != normText(existing.GoodreadsID))
	add(OverrideOpenlibraryID, normText(params.OpenlibraryID) != normText(existing.OpenlibraryID))
	add(OverrideGoogleBooksID, normText(params.GoogleBooksID) != normText(existing.GoogleBooksID))
	add(OverrideMangaType, normText(params.MangaType) != normText(existing.MangaType))
	add(OverrideReadingDirection, normText(params.ReadingDirection) != normText(existing.ReadingDirection))
	add(OverrideSeriesCount, normInt(params.SeriesCount) != normInt(existing.SeriesCount))
	add(OverrideVolume, normInt(params.Volume) != normInt(existing.Volume))
	add(OverrideImprint, normText(params.Imprint) != normText(existing.Imprint))
	add(OverrideAgeRating, normText(params.AgeRating) != normText(existing.AgeRating))
	add(OverrideWebURL, normText(params.WebUrl) != normText(existing.WebUrl))
	add(OverrideMetadataNotes, normText(params.MetadataNotes) != normText(existing.MetadataNotes))
	add(OverrideCommunityRating, normFloat(params.CommunityRating) != normFloat(existing.CommunityRating))
	add(OverrideStoryArc, normText(params.StoryArc) != normText(existing.StoryArc))
	add(OverrideIsBlackAndWhite, normBool(params.IsBlackAndWhite) != normBool(existing.IsBlackAndWhite))
	add(OverrideAlternateInfo, normBytes(params.AlternateInfo) != normBytes(existing.AlternateInfo))
	add(OverrideScanInformation, normText(params.ScanInformation) != normText(existing.ScanInformation))
	add(OverrideSummary, normText(params.Summary) != normText(existing.Summary))

	return changed
}

// DetectMetadataOverrides returns the union of the existing override set and
// any fields whose incoming (user-submitted) values differ from the stored
// row. Overrides accumulate: a field stays protected until an explicit reset,
// even if a later save reverts the value.
func DetectMetadataOverrides(params database.UpdateMediaItemParams, existing database.MediaItems) []string {
	return MergeOverrides(existing.MetadataOverrides, detectMetadataOverridesDiff(params, existing)...)
}

// ApplyMetadataOverrides restores every overridden field in params from the
// existing row so scanner updates cannot clobber user customizations. Derived
// search columns are restored together with their base column.
func ApplyMetadataOverrides(params *database.UpdateMediaItemParams, existing database.MediaItems) {
	o := existing.MetadataOverrides

	if hasOverride(o, OverrideTitle) {
		params.Title = existing.Title
	}
	if hasOverride(o, OverrideAuthor) {
		params.Author = existing.Author
	}
	if hasOverride(o, OverrideISBN) {
		params.Isbn = existing.Isbn
	}
	if hasOverride(o, OverrideDescription) {
		params.Description = existing.Description
	}
	if hasOverride(o, OverrideCoverImagePath) {
		params.CoverImagePath = existing.CoverImagePath
	}
	if hasOverride(o, OverrideSeries) {
		params.Series = existing.Series
	}
	if hasOverride(o, OverrideSeriesNumber) {
		params.SeriesNumber = existing.SeriesNumber
	}
	if hasOverride(o, OverrideTags) {
		params.Tags = existing.Tags
		params.TagsSearch = existing.TagsSearch
	}
	if hasOverride(o, OverrideAsin) {
		params.Asin = existing.Asin
	}
	if hasOverride(o, OverrideDatePublished) {
		params.DatePublished = existing.DatePublished
	}
	if hasOverride(o, OverridePublisher) {
		params.Publisher = existing.Publisher
	}
	if hasOverride(o, OverrideContributors) {
		params.Contributors = existing.Contributors
		params.ContributorsSearch = existing.ContributorsSearch
	}
	if hasOverride(o, OverrideLanguage) {
		params.Language = existing.Language
	}
	if hasOverride(o, OverrideEdition) {
		params.Edition = existing.Edition
	}
	if hasOverride(o, OverridePageCount) {
		params.PageCount = existing.PageCount
	}
	if hasOverride(o, OverrideGenre) {
		params.Genre = existing.Genre
	}
	if hasOverride(o, OverrideCopyrightYear) {
		params.CopyrightYear = existing.CopyrightYear
	}
	if hasOverride(o, OverrideGoodreadsID) {
		params.GoodreadsID = existing.GoodreadsID
	}
	if hasOverride(o, OverrideOpenlibraryID) {
		params.OpenlibraryID = existing.OpenlibraryID
	}
	if hasOverride(o, OverrideGoogleBooksID) {
		params.GoogleBooksID = existing.GoogleBooksID
	}
	if hasOverride(o, OverrideMangaType) {
		params.MangaType = existing.MangaType
	}
	if hasOverride(o, OverrideReadingDirection) {
		params.ReadingDirection = existing.ReadingDirection
	}
	if hasOverride(o, OverrideSeriesCount) {
		params.SeriesCount = existing.SeriesCount
	}
	if hasOverride(o, OverrideVolume) {
		params.Volume = existing.Volume
	}
	if hasOverride(o, OverrideImprint) {
		params.Imprint = existing.Imprint
	}
	if hasOverride(o, OverrideAgeRating) {
		params.AgeRating = existing.AgeRating
	}
	if hasOverride(o, OverrideWebURL) {
		params.WebUrl = existing.WebUrl
	}
	if hasOverride(o, OverrideMetadataNotes) {
		params.MetadataNotes = existing.MetadataNotes
	}
	if hasOverride(o, OverrideCommunityRating) {
		params.CommunityRating = existing.CommunityRating
	}
	if hasOverride(o, OverrideStoryArc) {
		params.StoryArc = existing.StoryArc
	}
	if hasOverride(o, OverrideIsBlackAndWhite) {
		params.IsBlackAndWhite = existing.IsBlackAndWhite
	}
	if hasOverride(o, OverrideAlternateInfo) {
		params.AlternateInfo = existing.AlternateInfo
	}
	if hasOverride(o, OverrideScanInformation) {
		params.ScanInformation = existing.ScanInformation
	}
	if hasOverride(o, OverrideSummary) {
		params.Summary = existing.Summary
	}
}