package services

import (
	"bookhoard/internal/database"
	"bookhoard/internal/utils"
	"context"

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

type SeriesInfo struct {
	Name          string
	LibraryID     string
	BookCount     int64
	TotalInSeries int
	CoverPaths    []string
	LastEntryAt   string
	// Viewer-scoped progress aggregates (requesting user): books
	// finished (percentage >= 0.999) and the series' most recent read.
	ReadCount  int64
	LastReadAt string
}

// SeriesPageOptions carries the series page's sort/filter state. Zero
// values mean defaults (recent, no filters). Extensible by design:
// adding a sort = one entry in seriesSortKeys + a matching CASE arm in
// queries.sql (GetDistinctSeries) + one <option> in templates/
// series.templ; adding a filter = a param on this struct threaded into
// the query's WHERE/HAVING. Unknown values resolve to defaults, so a
// stale URL or hand-rolled API call can never reach the SQL with an
// unhandled key.
type SeriesPageOptions struct {
	Sort         string // registry key, resolved by ResolveSeriesSort
	Query        string // series-name substring
	Author       string // matches when ANY book's author matches
	Status       string // "" | unstarted | reading | finished
	ViewerUserID pgtype.UUID
}

// seriesSortKeys is the registry of sort= values the series page
// understands.
var seriesSortKeys = map[string]bool{
	"recent":         true, // default: newest series first
	"recent_asc":     true,
	"name_asc":       true,
	"name_desc":      true,
	"author_asc":     true,
	"author_desc":    true,
	"books_asc":      true,
	"books_desc":     true,
	"progress_asc":   true,
	"progress_desc":  true,
	"last_read_asc":  true,
	"last_read_desc": true,
}

// seriesStatusKeys is the registry of status= values. The three states
// are mutually exclusive and exhaustive: a series is finished when
// every owned book is, reading when any book sits between 0 and the
// finish threshold, unstarted when no book has progress > 0.
var seriesStatusKeys = map[string]bool{
	"unstarted": true,
	"reading":   true,
	"finished":  true,
}

// ResolveSeriesSort maps any unknown/empty sort to the default. It is
// the single source of truth backing both the SSR page and the JSON
// API — the SQL CASE cascade must contain an arm for every key here.
func ResolveSeriesSort(sort string) string {
	if seriesSortKeys[sort] {
		return sort
	}
	return "recent"
}

// nargText makes an optional text param: empty string → SQL NULL so
// the query's IS NULL guard skips the filter.
func nargText(v string) pgtype.Text {
	return pgtype.Text{String: v, Valid: v != ""}
}

type SeriesService struct {
	db *database.Queries
}

func NewSeriesService(db *database.Queries) *SeriesService {
	return &SeriesService{db: db}
}

// GetSeriesPage lists series grouped PER LIBRARY (same name in two
// libraries = two entries) filtered to the requester's visible libraries.
// Pass libraryID for a single-library page, or leave it invalid and pass
// visibleLibraryIDs for an across-my-libraries page. Both filters compose:
// the handler validates any explicit library_id against the visible set.
func (s *SeriesService) GetSeriesPage(ctx context.Context, libraryID pgtype.UUID, visibleLibraryIDs []pgtype.UUID, limit, offset int, opts SeriesPageOptions) ([]SeriesInfo, int, error) {
	sort := nargText(ResolveSeriesSort(opts.Sort))
	status := nargText("")
	if seriesStatusKeys[opts.Status] {
		status = nargText(opts.Status)
	}

	countParams := database.GetDistinctSeriesCountParams{
		ViewerUserID:      opts.ViewerUserID,
		LibraryID:         libraryID,
		VisibleLibraryIds: visibleLibraryIDs,
		SeriesQuery:       nargText(opts.Query),
		AuthorQuery:       nargText(opts.Author),
		Status:            status,
	}
	totalCount, err := s.db.GetDistinctSeriesCount(ctx, countParams)
	if err != nil {
		return nil, 0, err
	}

	rows, err := s.db.GetDistinctSeries(ctx, database.GetDistinctSeriesParams{
		ViewerUserID:      opts.ViewerUserID,
		LibraryID:         libraryID,
		VisibleLibraryIds: visibleLibraryIDs,
		SeriesQuery:       countParams.SeriesQuery,
		AuthorQuery:       countParams.AuthorQuery,
		Status:            status,
		Sort:              sort,
		Limit:             pgtype.Int4{Int32: int32(limit), Valid: true},
		Offset:            pgtype.Int4{Int32: int32(offset), Valid: true},
	})
	if err != nil {
		return nil, 0, err
	}

	var series []SeriesInfo
	for _, row := range rows {
		seriesName := row.Series.String
		coverPaths, _ := s.GetSeriesCovers(ctx, row.LibraryID, seriesName, 7)

		totalInSeries := 0
		if row.TotalInSeries != nil {
			if v, ok := row.TotalInSeries.(int32); ok {
				totalInSeries = int(v)
			} else if v, ok := row.TotalInSeries.(int64); ok {
				totalInSeries = int(v)
			}
		}

		lastEntry := ""
		if row.LastEntryAt != nil {
			switch v := row.LastEntryAt.(type) {
			case pgtype.Timestamptz:
				if v.Valid {
					lastEntry = v.Time.String()
				}
			case string:
				lastEntry = v
			}
		}

		lastRead := ""
		if row.LastReadAt != nil {
			switch v := row.LastReadAt.(type) {
			case pgtype.Timestamptz:
				if v.Valid {
					lastRead = v.Time.String()
				}
			case string:
				lastRead = v
			}
		}

		if totalInSeries == 0 || totalInSeries < int(row.BookCount) {
			totalInSeries = int(row.BookCount)
		}

		series = append(series, SeriesInfo{
			Name:          seriesName,
			LibraryID:     uuidFromPG(row.LibraryID),
			BookCount:     row.BookCount,
			TotalInSeries: totalInSeries,
			CoverPaths:    coverPaths,
			LastEntryAt:   lastEntry,
			ReadCount:     row.FinishedCount,
			LastReadAt:    lastRead,
		})
	}

	if series == nil {
		series = []SeriesInfo{}
	}

	return series, int(totalCount), nil
}

func (s *SeriesService) GetSeriesCovers(ctx context.Context, libraryID pgtype.UUID, seriesName string, limit int) ([]string, error) {
	covers, err := s.db.GetSeriesCovers(ctx, database.GetSeriesCoversParams{
		LibraryID: libraryID,
		Series:    pgtype.Text{String: seriesName, Valid: true},
		Limit:     pgtype.Int4{Int32: int32(limit), Valid: true},
	})
	if err != nil {
		return nil, err
	}

	paths := make([]string, 0, len(covers))
	for _, c := range covers {
		resolved := utils.ResolveMediaURL(c.LibraryID, c.CoverImagePath)
		if resolved != "" {
			paths = append(paths, resolved)
		}
	}

	return paths, nil
}

func (s *SeriesService) GetSeriesBooks(ctx context.Context, libraryID pgtype.UUID, seriesName string) ([]database.MediaItems, error) {
	return s.db.GetSeriesBooks(ctx, database.GetSeriesBooksParams{
		Series:    pgtype.Text{String: seriesName, Valid: true},
		LibraryID: libraryID,
	})
}

// VisibleLibraries exposes the per-user visibility set used by the series
// handlers to scope listings and validate explicit library_id params.
func (s *SeriesService) VisibleLibraries(ctx context.Context, userID pgtype.UUID) ([]database.GetUserVisibleLibrariesRow, error) {
	return s.db.GetUserVisibleLibraries(ctx, userID)
}

func uuidFromPG(id pgtype.UUID) string {
	if !id.Valid {
		return ""
	}
	u, err := uuid.FromBytes(id.Bytes[0:16])
	if err != nil {
		return ""
	}
	return u.String()
}

func continueSeriesRowToMediaItems(row database.GetContinueSeriesItemsRow) database.MediaItems {
	return database.MediaItems{
		ID: row.ID, LibraryID: row.LibraryID, Title: row.Title, Author: row.Author,
		Isbn: row.Isbn, Description: row.Description, FilePath: row.FilePath,
		FileSize: row.FileSize, MimeType: row.MimeType, CoverImagePath: row.CoverImagePath,
		Series: row.Series, SeriesNumber: row.SeriesNumber, Tags: row.Tags, Asin: row.Asin,
		DatePublished: row.DatePublished, Publisher: row.Publisher, Contributors: row.Contributors,
		Language: row.Language, Edition: row.Edition, PageCount: row.PageCount,
		Genre: row.Genre, CopyrightYear: row.CopyrightYear, GoodreadsID: row.GoodreadsID,
		OpenlibraryID: row.OpenlibraryID, GoogleBooksID: row.GoogleBooksID,
		AddedByAdminID: row.AddedByAdminID, CreatedAt: row.CreatedAt, UpdatedAt: row.UpdatedAt,
		FormatGroup: row.FormatGroup, FormatMimetype: row.FormatMimetype,
		IsReflowable: row.IsReflowable, HasFixedLayout: row.HasFixedLayout,
		TotalCharacters: row.TotalCharacters, ChapterCount: row.ChapterCount,
		EntitlementID: row.EntitlementID, RevisionNumber: row.RevisionNumber,
		KoboContentID: row.KoboContentID, KoboMetadata: row.KoboMetadata,
		MangaType: row.MangaType, ReadingDirection: row.ReadingDirection,
		SeriesCount: row.SeriesCount, Volume: row.Volume, Imprint: row.Imprint,
		AgeRating: row.AgeRating, WebUrl: row.WebUrl, StoryArc: row.StoryArc,
		IsBlackAndWhite: row.IsBlackAndWhite, MetadataNotes: row.MetadataNotes,
		CommunityRating: row.CommunityRating, AlternateInfo: row.AlternateInfo,
		ScanInformation: row.ScanInformation, Summary: row.Summary,
		ChapterMetadata: row.ChapterMetadata, LibraryTypeName: row.LibraryTypeName,
		TagsSearch: row.TagsSearch, ContributorsSearch: row.ContributorsSearch,
		FileSha256: row.FileSha256, OpfIdentifier: row.OpfIdentifier,
		OpfUuid: row.OpfUuid, HashConfidence: row.HashConfidence,
	}
}