package repository

import (
	"context"
	"encoding/json"
	"errors"
	"strings"

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

// BannerWriteInput is create/update payload for ops_banners.
type BannerWriteInput struct {
	Code      string
	Title     string
	Placement string
	ImageURL  *string
	LinkPath  *string
	SortOrder int
	Active    bool
}

// ListActiveBanners returns active banners for a placement (C-end).
func (r *AdminRepo) ListActiveBanners(ctx context.Context, placement string) ([]BannerRow, error) {
	rows, err := r.Pool.Query(ctx, `
		SELECT id, code, title, placement, image_url, link_path, sort_order, active, system, updated_at
		FROM ops_banners
		WHERE active = true AND placement = $1
		ORDER BY sort_order ASC, code ASC
		LIMIT 100`, placement)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []BannerRow
	for rows.Next() {
		var b BannerRow
		if err := rows.Scan(
			&b.ID, &b.Code, &b.Title, &b.Placement, &b.ImageURL, &b.LinkPath,
			&b.SortOrder, &b.Active, &b.System, &b.UpdatedAt,
		); err != nil {
			return nil, err
		}
		out = append(out, b)
	}
	return out, rows.Err()
}

// CreateBannerWithAudit inserts a banner and audits.
func (r *AdminRepo) CreateBannerWithAudit(
	ctx context.Context,
	adminID uuid.UUID,
	in BannerWriteInput,
	meta json.RawMessage,
) (*BannerRow, error) {
	tx, err := r.Pool.Begin(ctx)
	if err != nil {
		return nil, err
	}
	defer tx.Rollback(ctx)

	var b BannerRow
	err = tx.QueryRow(ctx, `
		INSERT INTO ops_banners(code, title, placement, image_url, link_path, sort_order, active, system)
		VALUES ($1,$2,$3,$4,$5,$6,$7,false)
		RETURNING id, code, title, placement, image_url, link_path, sort_order, active, system, updated_at`,
		in.Code, in.Title, in.Placement, in.ImageURL, in.LinkPath, in.SortOrder, in.Active,
	).Scan(
		&b.ID, &b.Code, &b.Title, &b.Placement, &b.ImageURL, &b.LinkPath,
		&b.SortOrder, &b.Active, &b.System, &b.UpdatedAt,
	)
	if err != nil {
		return nil, mapBannerWriteErr(err)
	}
	if meta == nil {
		meta = json.RawMessage(`{}`)
	}
	if _, err := tx.Exec(ctx, `
		INSERT INTO admin_audit_logs(admin_id, action, target_type, target_id, meta)
		VALUES ($1,'cms.banner.create','banner',$2,$3)`,
		adminID, b.ID.String(), meta,
	); err != nil {
		return nil, err
	}
	if err := tx.Commit(ctx); err != nil {
		return nil, err
	}
	return &b, nil
}

// UpdateBannerWithAudit updates mutable fields and audits.
func (r *AdminRepo) UpdateBannerWithAudit(
	ctx context.Context,
	adminID, id uuid.UUID,
	in BannerWriteInput,
	meta json.RawMessage,
) (*BannerRow, error) {
	tx, err := r.Pool.Begin(ctx)
	if err != nil {
		return nil, err
	}
	defer tx.Rollback(ctx)

	var system bool
	var oldCode string
	err = tx.QueryRow(ctx, `SELECT system, code FROM ops_banners WHERE id=$1`, id).Scan(&system, &oldCode)
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, pgx.ErrNoRows
	}
	if err != nil {
		return nil, err
	}
	code := in.Code
	if system {
		code = oldCode
	}

	var b BannerRow
	err = tx.QueryRow(ctx, `
		UPDATE ops_banners
		SET code=$2, title=$3, placement=$4, image_url=$5, link_path=$6,
		    sort_order=$7, active=$8, updated_at=now()
		WHERE id=$1
		RETURNING id, code, title, placement, image_url, link_path, sort_order, active, system, updated_at`,
		id, code, in.Title, in.Placement, in.ImageURL, in.LinkPath, in.SortOrder, in.Active,
	).Scan(
		&b.ID, &b.Code, &b.Title, &b.Placement, &b.ImageURL, &b.LinkPath,
		&b.SortOrder, &b.Active, &b.System, &b.UpdatedAt,
	)
	if err != nil {
		return nil, mapBannerWriteErr(err)
	}
	if meta == nil {
		meta = json.RawMessage(`{}`)
	}
	if _, err := tx.Exec(ctx, `
		INSERT INTO admin_audit_logs(admin_id, action, target_type, target_id, meta)
		VALUES ($1,'cms.banner.update','banner',$2,$3)`,
		adminID, id.String(), meta,
	); err != nil {
		return nil, err
	}
	if err := tx.Commit(ctx); err != nil {
		return nil, err
	}
	return &b, nil
}

func mapBannerWriteErr(err error) error {
	var pgErr *pgconn.PgError
	if errors.As(err, &pgErr) && pgErr.Code == "23505" {
		return errString("banner code conflict")
	}
	return err
}

// BannerCodeConflict reports unique code violation.
func BannerCodeConflict(err error) bool {
	return err != nil && strings.Contains(err.Error(), "banner code conflict")
}