package repository

import (
	"context"
	"strings"

	"gorm.io/gorm"
)

// AdminRecordCard 是「文章管理」混合列表的统一卡片：跨 brand_runways 与 street_snaps
// 两张表，字段取两者并集的最小可读子集（类型由 Kind 区分）。
//
// 为什么是 UNION 而非分别查两张表再在 Go 里拼：混合列表需要按（待审优先 + id 倒序）
// 做跨表统一排序与分页，分别查两表再分页会得到错误的边界；一条 UNION 查询在数据库侧
// 完成排序与 LIMIT/OFFSET，分页语义才正确，也避免把整张表拉进内存。
type AdminRecordCard struct {
	Kind       string // "runway" | "street"
	ID         uint32 // 内部数值主键（供通过/驳回/批量接口使用）
	Title      string
	Subtitle   string // 走秀=品牌名；街拍=城市
	ImageCount int
	Status     string // pending / published / rejected
}

// DupStat 某记录的图片去重统计（仅统计 is_deleted=0 的存活行）。
type DupStat struct {
	Total int // 存活图片总数（含主图与细节图）
	Dup   int // is_duplicate=1 的张数
}

// AdminRepository 文章管理页所需的跨表只读查询。
type AdminRepository interface {
	// ListMixed 按状态 + 类型过滤（status 为空表示全部；kind 为空表示走秀+街拍，
	// "runway"/"street" 则只取对应一类），跨表统一排序后分页返回。
	// 排序：pending 优先，其次 id 倒序（最新待审排最前）。
	ListMixed(ctx context.Context, status, kind string, page, size int) ([]AdminRecordCard, int64, error)
	// CountMixed 统计某状态 + 类型下的记录总数（用于 tab 角标）。
	CountMixed(ctx context.Context, status, kind string) (int64, error)
	// DupRateByRecords 批量统计若干记录的图片去重情况（仅存活行）。
	// 返回 owner id → {Total 存活图片总数, Dup is_duplicate=1 张数}；不存在的 id 不出现在 map 中。
	DupRateByRecords(ctx context.Context, kind string, ids []uint32) (map[uint32]DupStat, error)
}

type adminRepository struct {
	db *gorm.DB
}

// NewAdminRepository 创建文章管理仓储。
func NewAdminRepository(db *gorm.DB) AdminRepository {
	return &adminRepository{db: db}
}

// legWhere 单条腿（带表别名）的过滤条件：is_deleted=0 是后台可见性的硬约束，
// status 过滤可选。别名必须显式指定——两表 LEFT JOIN 时 is_deleted 会歧义。
func legWhere(alias, status string) (string, []interface{}) {
	where := alias + ".is_deleted = 0"
	args := []interface{}{}
	if status != "" {
		where += " AND " + alias + ".status = ?"
		args = append(args, status)
	}
	return where, args
}

func (r *adminRepository) ListMixed(ctx context.Context, status, kind string, page, size int) ([]AdminRecordCard, int64, error) {
	if page < 1 {
		page = 1
	}
	if size < 1 {
		size = 24
	}
	rw, rargs := legWhere("r", status)
	sw, sargs := legWhere("s", status)

	// kind 决定本次跨表 UNION 取哪几腿：""=两表都取，"street"=只取街拍，"runway"=只取走秀。
	var legs []string
	var args []interface{}
	if kind != "street" {
		legs = append(legs, `
			SELECT 'runway' AS kind, r.id, COALESCE(r.title_en, '') AS title, COALESCE(b.name_en, '') AS subtitle,
			       CAST(r.image_count AS BIGINT) AS image_count, r.status
			FROM brand_runways r
			LEFT JOIN brands b ON b.id = r.brand_id
			WHERE `+rw)
		args = append(args, rargs...)
	}
	if kind != "runway" {
		legs = append(legs, `
			SELECT 'street' AS kind, s.id, COALESCE(s.title, '') AS title, COALESCE(s.city, '') AS subtitle,
			       CAST(s.image_count AS BIGINT) AS image_count, s.status
			FROM street_snaps s
			WHERE `+sw)
		args = append(args, sargs...)
	}

	q := `
		SELECT * FROM (` + strings.Join(legs, " UNION ALL ") + `) sub
		ORDER BY (status = 'pending') DESC, id DESC
		LIMIT ? OFFSET ?`
	listArgs := append(append([]interface{}{}, args...), size, (page-1)*size)

	var cards []AdminRecordCard
	if err := r.db.WithContext(ctx).Raw(q, listArgs...).Scan(&cards).Error; err != nil {
		return nil, 0, err
	}

	total, err := r.CountMixed(ctx, status, kind)
	if err != nil {
		return nil, 0, err
	}
	return cards, total, nil
}

// DupRateByRecords 批量统计若干记录的图片去重情况。
// kind=runway 查 brand_runway_images（外键 runway_id）；kind=street 查 street_snap_images（外键 snap_id）。
// 只统计 is_deleted=0 的存活行；命中阈值为 phash.DefaultThreshold（当前 4）。
func (r *adminRepository) DupRateByRecords(ctx context.Context, kind string, ids []uint32) (map[uint32]DupStat, error) {
	out := make(map[uint32]DupStat)
	if len(ids) == 0 {
		return out, nil
	}
	var table, fk string
	switch kind {
	case "runway":
		table, fk = "brand_runway_images", "runway_id"
	case "street":
		table, fk = "street_snap_images", "snap_id"
	default:
		return out, nil
	}
	type agg struct {
		Owner uint32 `gorm:"column:owner"`
		Total int    `gorm:"column:total"`
		Dup   int    `gorm:"column:dup"`
	}
	var rows []agg
	if err := r.db.WithContext(ctx).
		Table(table).
		Select(fk + " AS owner, COUNT(*) AS total, COALESCE(SUM(CASE WHEN is_duplicate = 1 THEN 1 ELSE 0 END), 0) AS dup").
		Where(fk+" IN ? AND is_deleted = 0", ids).
		Group(fk).
		Scan(&rows).Error; err != nil {
		return nil, err
	}
	for _, row := range rows {
		out[row.Owner] = DupStat{Total: row.Total, Dup: row.Dup}
	}
	return out, nil
}

func (r *adminRepository) CountMixed(ctx context.Context, status, kind string) (int64, error) {
	rw, rargs := legWhere("r", status)
	sw, sargs := legWhere("s", status)

	var legs []string
	var args []interface{}
	if kind != "street" {
		legs = append(legs, `SELECT COUNT(*) AS c FROM brand_runways r WHERE `+rw)
		args = append(args, rargs...)
	}
	if kind != "runway" {
		legs = append(legs, `SELECT COUNT(*) AS c FROM street_snaps s WHERE `+sw)
		args = append(args, sargs...)
	}
	q := `
		SELECT COALESCE(SUM(c), 0) FROM (` + strings.Join(legs, " UNION ALL ") + `) t`
	var total int64
	if err := r.db.WithContext(ctx).Raw(q, args...).Scan(&total).Error; err != nil {
		return 0, err
	}
	return total, nil
}