// Package notes 存放站长为地点加的别名与备注。
//
// 备注挂的是**坐标键**（place_key）而不是 rond 的地点编号：src_pk 只在单个数据集内有效
// （rond 每次导出都会重排 Z_PK，实测两份备份里 822 条到访的 UUID 一致而 Z_PK 100% 不同），
// 换个数据集同编号就是另一个地点，备注会全部失联。坐标是地理事实，跨数据集稳定。
package notes

import (
	"context"
	"database/sql"
	"fmt"
	"strings"
	"time"
)

type Note struct {
	SrcPK     int
	Alias     string
	Content   string
	RondNote  string
	UpdatedAt time.Time
}

type Store struct{ DB *sql.DB }

// placeKeyExpr 把某个 places 别名下的坐标换算成 place_key。
// **必须与 Go 侧的 rond.PlaceCoordKey 逐位一致**：
//
//	fmt.Sprintf("%.6f|%.6f")  ↔  to_char(x,'FM999990.000000')||'|'||to_char(y,'FM999990.000000')
//
// 已在真实数据上逐条比对（368/368 相同）。改任何一边都要重新比。
func placeKeyExpr(alias string) string {
	return fmt.Sprintf(
		"to_char(%[1]s.lat,'FM999990.000000')||'|'||to_char(%[1]s.lon,'FM999990.000000')", alias)
}

// All 返回某个数据集里「有备注的地点」，键是地点在该数据集内的编号。
// 站点只有一个站长账号，读的时候不按 user_id 过滤（匿名访客也要看到别名）。
func (s *Store) All(ctx context.Context, datasetID int64) (map[int]Note, error) {
	out := map[int]Note{}
	rows, err := s.DB.QueryContext(ctx, `
		SELECT p.src_pk, n.alias, n.note, n.rond_note, n.updated_at
		FROM places p
		JOIN place_notes n ON n.place_key = `+placeKeyExpr("p")+`
		WHERE p.dataset_id = $1 AND p.lat IS NOT NULL AND p.lon IS NOT NULL`, datasetID)
	if err != nil {
		return out, err
	}
	defer rows.Close()
	for rows.Next() {
		var n Note
		if err := rows.Scan(&n.SrcPK, &n.Alias, &n.Content, &n.RondNote, &n.UpdatedAt); err != nil {
			return out, err
		}
		out[n.SrcPK] = n
	}
	return out, rows.Err()
}

// SetNote 只改备注、保留别名（批量「清空备注」用）；两者都为空则删除记录。
func (s *Store) SetNote(ctx context.Context, userID, datasetID int64, srcPK int, content string) error {
	var alias string
	err := s.DB.QueryRowContext(ctx, `SELECT n.alias FROM place_notes n
		JOIN places p ON n.place_key = `+placeKeyExpr("p")+`
		WHERE n.user_id=$1 AND p.dataset_id=$2 AND p.src_pk=$3`, userID, datasetID, srcPK).Scan(&alias)
	if err != nil && err != sql.ErrNoRows {
		return err
	}
	return s.Save(ctx, userID, datasetID, srcPK, alias, content)
}

// Delete 删除某地点的整条备注与别名。
func (s *Store) Delete(ctx context.Context, userID, datasetID int64, srcPK int) error {
	_, err := s.DB.ExecContext(ctx, `DELETE FROM place_notes n USING places p
		WHERE n.user_id=$1 AND p.dataset_id=$2 AND p.src_pk=$3
		  AND n.place_key = `+placeKeyExpr("p"), userID, datasetID, srcPK)
	return err
}

// Save 写入别名与备注；两者都为空时清空手写内容（rond 回填的那一块要留着）。
func (s *Store) Save(ctx context.Context, userID, datasetID int64, srcPK int, alias, content string) error {
	alias = strings.TrimSpace(alias)
	content = strings.TrimSpace(content)
	if alias == "" && content == "" {
		// 没有 rond 备注时直接删行；有则只清空手写部分，别把回填结果一起删掉
		if _, err := s.DB.ExecContext(ctx, `DELETE FROM place_notes n USING places p
			WHERE n.user_id=$1 AND p.dataset_id=$2 AND p.src_pk=$3
			  AND n.place_key = `+placeKeyExpr("p")+` AND n.rond_note=''`,
			userID, datasetID, srcPK); err != nil {
			return err
		}
		_, err := s.DB.ExecContext(ctx, `UPDATE place_notes n
			SET alias='', note='', updated_at=now()
			FROM places p
			WHERE n.user_id=$1 AND p.dataset_id=$2 AND p.src_pk=$3
			  AND n.place_key = `+placeKeyExpr("p"), userID, datasetID, srcPK)
		return err
	}
	// 先按坐标键算出这条地点该挂在哪，找不到该地点就什么也不写
	_, err := s.DB.ExecContext(ctx, `INSERT INTO place_notes
			(user_id, place_key, dataset_id, src_pk, alias, note, updated_at)
		SELECT $1, `+placeKeyExpr("p")+`, $2, $3, $4, $5, now()
		FROM places p
		WHERE p.dataset_id=$2 AND p.src_pk=$3 AND p.lat IS NOT NULL AND p.lon IS NOT NULL
		ON CONFLICT (user_id, place_key) DO UPDATE SET
			alias=EXCLUDED.alias, note=EXCLUDED.note,
			dataset_id=EXCLUDED.dataset_id, src_pk=EXCLUDED.src_pk, updated_at=now()`,
		userID, datasetID, srcPK, alias, content)
	return err
}

// BackfillRond 把 rond 备份里按次到访记录的备注（ZVISIT.ZREMARK_）汇总进 rond_note：
// 同一地点多条备注全部保留，去重后按时间升序、每条一行并带上日期。
// 只重写 rond_note 一列，站长手写的 note 一概不动。返回写了多少行。
func (s *Store) BackfillRond(ctx context.Context, userID, datasetID int64) (int, error) {
	// DISTINCT 在「日期 + 内容」这一层做，同一天重复写的同一句只留一条
	agg := `
	WITH raw AS (
		SELECT ` + placeKeyExpr("p") + ` AS key,
		       to_char(v.arrival, 'YYYY-MM-DD') || ' ' || btrim(v.remark) AS line
		FROM visits v JOIN places p ON p.id = v.place_id
		WHERE v.dataset_id = $1 AND btrim(COALESCE(v.remark, '')) <> ''
		  AND p.lat IS NOT NULL AND p.lon IS NOT NULL
	), uniq AS (
		SELECT DISTINCT key, line, left(line, 10) AS day FROM raw
	), agg AS (
		SELECT key, string_agg(line, E'\n' ORDER BY day, line) AS txt FROM uniq GROUP BY key
	)`
	res, err := s.DB.ExecContext(ctx, agg+`
		INSERT INTO place_notes (user_id, place_key, dataset_id, src_pk, alias, note, rond_note, updated_at)
		SELECT $2, key, $1, 0, '', '', txt, now() FROM agg
		ON CONFLICT (user_id, place_key) DO UPDATE SET rond_note = EXCLUDED.rond_note`,
		datasetID, userID)
	if err != nil {
		return 0, err
	}
	affected, _ := res.RowsAffected()

	// 备注被删掉的地点要清掉旧值，否则会一直留着过期的 rond 内容。
	// 限定在本数据集的地点里：datasetID 不合法时子查询为空，一行都不会动。
	if _, err := s.DB.ExecContext(ctx, `
		UPDATE place_notes n SET rond_note = ''
		WHERE n.user_id = $2 AND n.rond_note <> ''
		  AND n.place_key IN (SELECT `+placeKeyExpr("p")+`
			FROM places p WHERE p.dataset_id = $1 AND p.lat IS NOT NULL AND p.lon IS NOT NULL)
		  AND NOT EXISTS (
			SELECT 1 FROM visits v JOIN places p ON p.id = v.place_id
			WHERE v.dataset_id = $1 AND `+placeKeyExpr("p")+` = n.place_key
			  AND btrim(COALESCE(v.remark, '')) <> ''
		  )`, datasetID, userID); err != nil {
		return 0, err
	}
	return int(affected), nil
}