package store

import (
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"strings"
	"time"
)

// Repo 表示一个 Git 仓库。
type Repo struct {
	ID            int64
	Name          string
	Description   string
	OwnerID       *int64
	DefaultBranch string
	IsArchived    bool
	AIEnabled     bool
	CreatedAt     time.Time
	UpdatedAt     time.Time
}

// RepoCard 是首页 / 后台列表用的仓库条目（附带展示统计）。
type RepoCard struct {
	Repo
	OwnerName    string
	PushCount    int
	LastPushAt   time.Time
	LastWhatsNew string
	LastPusher   string
}

// CreateRepo 新建仓库记录。
func (s *Store) CreateRepo(name, description string, ownerID int64) (*Repo, error) {
	ts := nowString()
	res, err := s.db.Exec(`INSERT INTO repos(name, description, owner_id, default_branch, created_at, updated_at)
		VALUES(?, ?, ?, 'main', ?, ?)`, name, description, ownerID, ts, ts)
	if err != nil {
		if isUniqueErr(err) {
			return nil, fmt.Errorf("项目 %q 已存在", name)
		}
		return nil, err
	}
	id, _ := res.LastInsertId()
	return s.RepoByID(id)
}

const repoCols = `id, name, description, owner_id, default_branch, is_archived, ai_enabled, created_at, updated_at`

func scanRepo(row interface {
	Scan(dest ...any) error
}) (*Repo, error) {
	var r Repo
	var owner sql.NullInt64
	var archived, ai int
	var created, updated string
	if err := row.Scan(&r.ID, &r.Name, &r.Description, &owner, &r.DefaultBranch, &archived, &ai, &created, &updated); err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, ErrNotFound
		}
		return nil, err
	}
	if owner.Valid {
		id := owner.Int64
		r.OwnerID = &id
	}
	r.IsArchived = archived == 1
	r.AIEnabled = ai == 1
	r.CreatedAt = parseTime(created)
	r.UpdatedAt = parseTime(updated)
	return &r, nil
}

// RepoByID 按主键查询仓库。
func (s *Store) RepoByID(id int64) (*Repo, error) {
	return scanRepo(s.db.QueryRow(`SELECT `+repoCols+` FROM repos WHERE id = ?`, id))
}

// RepoByName 按名称查询仓库（不区分大小写）。
func (s *Store) RepoByName(name string) (*Repo, error) {
	return scanRepo(s.db.QueryRow(`SELECT `+repoCols+` FROM repos WHERE name = ? COLLATE NOCASE`, name))
}

// ListRepos 返回仓库列表（含统计），q 非空时按名称/描述模糊搜索。
func (s *Store) ListRepos(q string) ([]*RepoCard, error) {
	query := `SELECT ` + repoCols + `,
		COALESCE((SELECT username FROM users u WHERE u.id = repos.owner_id), ''),
		(SELECT COUNT(*) FROM pushes p WHERE p.repo_id = repos.id),
		COALESCE((SELECT MAX(created_at) FROM pushes p WHERE p.repo_id = repos.id), repos.updated_at),
		COALESCE((SELECT whats_new FROM pushes p WHERE p.repo_id = repos.id ORDER BY id DESC LIMIT 1), ''),
		COALESCE((SELECT actor_display FROM pushes p WHERE p.repo_id = repos.id ORDER BY id DESC LIMIT 1), '')
		FROM repos`
	var args []any
	if strings.TrimSpace(q) != "" {
		like := "%" + strings.TrimSpace(q) + "%"
		query += ` WHERE name LIKE ? OR description LIKE ?`
		args = append(args, like, like)
	}
	query += ` ORDER BY updated_at DESC, name COLLATE NOCASE ASC`
	rows, err := s.db.Query(query, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []*RepoCard
	for rows.Next() {
		var c RepoCard
		var owner sql.NullInt64
		var archived, ai int
		var created, updated, lastPush string
		if err := rows.Scan(&c.ID, &c.Name, &c.Description, &owner, &c.DefaultBranch, &archived, &ai,
			&created, &updated, &c.OwnerName, &c.PushCount, &lastPush, &c.LastWhatsNew, &c.LastPusher); err != nil {
			return nil, err
		}
		if owner.Valid {
			id := owner.Int64
			c.OwnerID = &id
		}
		c.IsArchived = archived == 1
		c.AIEnabled = ai == 1
		c.CreatedAt = parseTime(created)
		c.UpdatedAt = parseTime(updated)
		c.LastPushAt = parseTime(lastPush)
		out = append(out, &c)
	}
	return out, rows.Err()
}

// UpdateRepo 保存仓库的可编辑字段。
//
// 注意：这里刻意不写 name。仓库名同时决定了磁盘上的目录
// （<data>/repos/<name>.git），如果这里允许改名而调用方忘了同步重命名
// 目录，数据库与磁盘就会脱钩，仓库直接变成"数据缺失"。
// 改名请走 RenameRepo —— 它把"改名字"和"改目录"作为同一个操作。
func (s *Store) UpdateRepo(r *Repo) error {
	b2i := func(b bool) int {
		if b {
			return 1
		}
		return 0
	}
	_, err := s.db.Exec(`UPDATE repos SET description = ?, default_branch = ?, is_archived = ?, ai_enabled = ?, updated_at = ? WHERE id = ?`,
		r.Description, r.DefaultBranch, b2i(r.IsArchived), b2i(r.AIEnabled), nowString(), r.ID)
	return err
}

// RenameRepo 修改仓库名。
//
// 调用方负责保证磁盘目录已经（或即将）同步到新名字；本方法只负责数据层。
func (s *Store) RenameRepo(id int64, newName string) error {
	res, err := s.db.Exec(`UPDATE repos SET name = ?, updated_at = ? WHERE id = ?`, newName, nowString(), id)
	if err != nil {
		if isUniqueErr(err) {
			return fmt.Errorf("项目 %q 已存在", newName)
		}
		return err
	}
	if n, _ := res.RowsAffected(); n == 0 {
		return ErrNotFound
	}
	return nil
}

// SetRepoOwner 单独更新仓库的所属者。
func (s *Store) SetRepoOwner(id int64, ownerID *int64) error {
	if ownerID == nil {
		_, err := s.db.Exec(`UPDATE repos SET owner_id = NULL WHERE id = ?`, id)
		return err
	}
	_, err := s.db.Exec(`UPDATE repos SET owner_id = ? WHERE id = ?`, *ownerID, id)
	return err
}

// TouchRepo 更新仓库的最近活跃时间。
func (s *Store) TouchRepo(id int64) error {
	_, err := s.db.Exec(`UPDATE repos SET updated_at = ? WHERE id = ?`, nowString(), id)
	return err
}

// DeleteRepo 删除仓库记录（git 目录由调用方清理）。
func (s *Store) DeleteRepo(id int64) error {
	_, err := s.db.Exec(`DELETE FROM repos WHERE id = ?`, id)
	return err
}

// PushCommit 是推送记录中单个提交的摘要（用于留痕展示）。
type PushCommit struct {
	SHA       string `json:"sha"`
	Subject   string `json:"subject"`
	Author    string `json:"author"`
	When      int64  `json:"when"`
	Additions int    `json:"additions"`
	Deletions int    `json:"deletions"`
	Files     int    `json:"files"`
}

// Push 表示一次推送事件。
type Push struct {
	ID            int64
	RepoID        int64
	RepoName      string
	UserID        *int64
	ActorUsername string
	ActorDisplay  string
	Ref           string
	OldSHA        string
	NewSHA        string
	CommitCount   int
	Details       []PushCommit
	WhatsNew      string
	AIStatus      string
	CreatedAt     time.Time
}

// CreatePush 记录一次推送。
func (s *Store) CreatePush(repoID int64, userID *int64, actorUsername, actorDisplay, ref, oldSHA, newSHA string, details []PushCommit) (*Push, error) {
	raw, _ := json.Marshal(details)
	res, err := s.db.Exec(`INSERT INTO pushes(repo_id, user_id, actor_username, actor_display, ref, old_sha, new_sha, commit_count, details, ai_status, created_at)
		VALUES(?, ?, ?, ?, ?, ?, ?, ?, ?, 'pending', ?)`,
		repoID, userID, actorUsername, actorDisplay, ref, oldSHA, newSHA, len(details), string(raw), nowString())
	if err != nil {
		return nil, err
	}
	id, _ := res.LastInsertId()
	return s.PushByID(id)
}

const pushCols = `p.id, p.repo_id, COALESCE(r.name, ''), p.user_id, p.actor_username, p.actor_display, p.ref, p.old_sha, p.new_sha,
	p.commit_count, p.details, p.whats_new, p.ai_status, p.created_at`

func scanPush(scan func(dest ...any) error) (*Push, error) {
	var p Push
	var userID sql.NullInt64
	var details, created string
	if err := scan(&p.ID, &p.RepoID, &p.RepoName, &userID, &p.ActorUsername, &p.ActorDisplay, &p.Ref,
		&p.OldSHA, &p.NewSHA, &p.CommitCount, &details, &p.WhatsNew, &p.AIStatus, &created); err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, ErrNotFound
		}
		return nil, err
	}
	if userID.Valid {
		id := userID.Int64
		p.UserID = &id
	}
	_ = json.Unmarshal([]byte(details), &p.Details)
	p.CreatedAt = parseTime(created)
	return &p, nil
}

// PushByID 按主键查询推送记录。
func (s *Store) PushByID(id int64) (*Push, error) {
	return scanPush(s.db.QueryRow(`SELECT `+pushCols+` FROM pushes p LEFT JOIN repos r ON r.id = p.repo_id WHERE p.id = ?`, id).Scan)
}

// PushesByRepo 返回某个仓库的推送记录。
func (s *Store) PushesByRepo(repoID int64, limit int) ([]*Push, error) {
	rows, err := s.db.Query(`SELECT `+pushCols+` FROM pushes p LEFT JOIN repos r ON r.id = p.repo_id
		WHERE p.repo_id = ? ORDER BY p.id DESC LIMIT ?`, repoID, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []*Push
	for rows.Next() {
		p, err := scanPush(rows.Scan)
		if err != nil {
			return nil, err
		}
		out = append(out, p)
	}
	return out, rows.Err()
}

// LatestPush 返回仓库最近一次推送，没有则返回 nil。
func (s *Store) LatestPush(repoID int64) (*Push, error) {
	p, err := scanPush(s.db.QueryRow(`SELECT `+pushCols+` FROM pushes p LEFT JOIN repos r ON r.id = p.repo_id
		WHERE p.repo_id = ? ORDER BY p.id DESC LIMIT 1`, repoID).Scan)
	if errors.Is(err, ErrNotFound) {
		return nil, nil
	}
	return p, err
}

// RecentPushes 返回全站最近的推送动态。
func (s *Store) RecentPushes(limit int) ([]*Push, error) {
	rows, err := s.db.Query(`SELECT `+pushCols+` FROM pushes p LEFT JOIN repos r ON r.id = p.repo_id
		ORDER BY p.id DESC LIMIT ?`, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []*Push
	for rows.Next() {
		p, err := scanPush(rows.Scan)
		if err != nil {
			return nil, err
		}
		out = append(out, p)
	}
	return out, rows.Err()
}

// SetPushSummary 写入 AI 生成的 whats new（或降级摘要）。
func (s *Store) SetPushSummary(id int64, whatsNew, status string) error {
	_, err := s.db.Exec(`UPDATE pushes SET whats_new = ?, ai_status = ? WHERE id = ?`, whatsNew, status, id)
	return err
}

// PushesByUser 返回某用户的推送数。
func (s *Store) PushesByUser(userID int64) (int, error) {
	var n int
	err := s.db.QueryRow(`SELECT COUNT(*) FROM pushes WHERE user_id = ?`, userID).Scan(&n)
	return n, err
}