// Package lidarrquarantine owns the per-user track quarantine workflow.
// Users flag a track as broken (Flag/Unflag), the SPA hides the track
// from their views, and admins resolve the resulting reports via the
// Service's admin actions (Resolve / DeleteFile / DeleteViaLidarr —
// the admin action methods are added in a follow-up task).
package lidarrquarantine

import (
	"context"
	"errors"
	"fmt"

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

	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
	"git.fabledsword.com/bvandeusen/minstrel/internal/lidarr"
	"git.fabledsword.com/bvandeusen/minstrel/internal/lidarrconfig"
)

// Public errors. Handlers map these to API codes.
var (
	ErrBadReason           = errors.New("lidarrquarantine: invalid reason")
	ErrTrackNotFound       = errors.New("lidarrquarantine: track not found")
	ErrQuarantineNotFound  = errors.New("lidarrquarantine: quarantine row not found")
	ErrAlbumMBIDMissing    = errors.New("lidarrquarantine: track has no parent album mbid")
	ErrLidarrAlbumNotFound = errors.New("lidarrquarantine: lidarr has no album for that mbid")
	ErrLidarrDisabled      = errors.New("lidarrquarantine: lidarr is not configured")
)

// Service owns the request lifecycle. clientFn is a per-call factory so
// config changes in lidarrconfig take effect immediately. clientFn returns
// nil when Lidarr is disabled.
type Service struct {
	pool      *pgxpool.Pool
	lidarrCfg *lidarrconfig.Service
	clientFn  func() *lidarr.Client
}

// NewService constructs a Service. Pass nil for clientFn to disable the
// Lidarr-using methods (DeleteViaLidarr will return ErrLidarrDisabled).
func NewService(pool *pgxpool.Pool, cfg *lidarrconfig.Service, clientFn func() *lidarr.Client) *Service {
	if clientFn == nil {
		clientFn = func() *lidarr.Client { return nil }
	}
	return &Service{pool: pool, lidarrCfg: cfg, clientFn: clientFn}
}

// Flag inserts or updates a quarantine row for the caller. Re-flagging
// the same (user, track) overwrites reason+notes (and bumps created_at).
func (s *Service) Flag(ctx context.Context, userID, trackID pgtype.UUID, reason string, notes string) (dbq.LidarrQuarantine, error) {
	if !validReason(reason) {
		return dbq.LidarrQuarantine{}, ErrBadReason
	}
	var notesPtr *string
	if notes != "" {
		notesPtr = &notes
	}
	row, err := dbq.New(s.pool).UpsertQuarantine(ctx, dbq.UpsertQuarantineParams{
		UserID:  userID,
		TrackID: trackID,
		Reason:  dbq.LidarrQuarantineReason(reason),
		Notes:   notesPtr,
	})
	if err != nil {
		// FK violation on track_id surfaces here as a postgres error;
		// callers can treat any error as "track doesn't exist or DB issue."
		// Distinguishing FK violation specifically isn't worth the extra
		// dependency on pgconn just for one branch.
		return dbq.LidarrQuarantine{}, fmt.Errorf("upsert: %w", err)
	}
	return row, nil
}

// Unflag removes the caller's row. Returns ErrQuarantineNotFound if no
// row exists for that (user, track).
func (s *Service) Unflag(ctx context.Context, userID, trackID pgtype.UUID) error {
	_, err := dbq.New(s.pool).DeleteQuarantine(ctx, dbq.DeleteQuarantineParams{
		UserID: userID, TrackID: trackID,
	})
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return ErrQuarantineNotFound
		}
		return fmt.Errorf("delete: %w", err)
	}
	return nil
}

// ListMine returns the caller's quarantines with track + album + artist
// detail. Drives /library/hidden. Ordered newest-first.
func (s *Service) ListMine(ctx context.Context, userID pgtype.UUID) ([]dbq.ListQuarantineForUserRow, error) {
	return dbq.New(s.pool).ListQuarantineForUser(ctx, userID)
}

// AdminQueueRow is the assembled aggregated row served by the admin
// queue endpoint. The handler post-processes the SQL result + a per-track
// ListQuarantineReports call to materialize reason_counts and the
// per-user reports list.
type AdminQueueRow struct {
	TrackID         pgtype.UUID
	TrackTitle      string
	ArtistName      string
	AlbumTitle      *string
	AlbumID         pgtype.UUID
	LidarrAlbumMBID *string
	ReportCount     int32
	LatestAt        pgtype.Timestamptz
	ReasonCounts    map[string]int
	Reports         []UserReport
}

// UserReport is the per-user detail under an aggregated admin row.
type UserReport struct {
	UserID    pgtype.UUID
	Username  string
	Reason    string
	Notes     *string
	CreatedAt pgtype.Timestamptz
}

// ListAdminQueue returns the aggregated admin queue. One row per track.
// Performs an N+1 (one ListQuarantineReportsForTrack per aggregated row)
// because materializing reason_counts in pure SQL is awkward; the queue
// is small in practice (≲100 tracks at household scale). Revisit with
// json_object_agg if the queue grows.
func (s *Service) ListAdminQueue(ctx context.Context) ([]AdminQueueRow, error) {
	q := dbq.New(s.pool)
	aggregated, err := q.ListAdminQuarantineQueue(ctx)
	if err != nil {
		return nil, fmt.Errorf("aggregate: %w", err)
	}
	out := make([]AdminQueueRow, 0, len(aggregated))
	for _, r := range aggregated {
		reports, err := q.ListQuarantineReportsForTrack(ctx, r.TrackID)
		if err != nil {
			return nil, fmt.Errorf("reports for track %v: %w", r.TrackID, err)
		}
		rc := make(map[string]int, len(reports))
		userReports := make([]UserReport, 0, len(reports))
		for _, rep := range reports {
			rc[string(rep.Reason)]++
			userReports = append(userReports, UserReport{
				UserID:    rep.UserID,
				Username:  rep.Username,
				Reason:    string(rep.Reason),
				Notes:     rep.Notes,
				CreatedAt: rep.CreatedAt,
			})
		}
		var albumTitle *string
		if r.AlbumTitle != "" {
			t := r.AlbumTitle
			albumTitle = &t
		}
		out = append(out, AdminQueueRow{
			TrackID:         r.TrackID,
			TrackTitle:      r.TrackTitle,
			ArtistName:      r.ArtistName,
			AlbumTitle:      albumTitle,
			AlbumID:         r.AlbumID,
			LidarrAlbumMBID: r.LidarrAlbumMbid,
			ReportCount:     r.ReportCount,
			LatestAt:        r.LatestAt,
			ReasonCounts:    rc,
			Reports:         userReports,
		})
	}
	return out, nil
}

func validReason(r string) bool {
	switch r {
	case "bad_rip", "wrong_file", "wrong_tags", "duplicate", "other":
		return true
	}
	return false
}