Cyrene_v2/internal/runtime/memory/projectindex/project.go

package projectindex

import (
	"context"
	"crypto/rand"
	"database/sql"
	"encoding/hex"
	"errors"
	"fmt"
	"strings"
	"time"
)

// Project 是一个项目索引条目（design §3）：链接其
// 各章节的项目标示，连同项目描述。它是层级的第 1 层（索引
// 条目）与第 2 层（描述）。零值不是
// 合法项目：ID 与 Title 必填。
type Project struct {
	ID        string
	Title     string
	Desc      string
	CreatedAt time.Time
	UpdatedAt time.Time
}

// PutProject 按 id upsert p。id 已存在时更新 title、desc 与
// updated_at，并保留原始的 created_at；id 为新值时
// 补齐缺失时间戳并插入。id 或 title 为空返回 ErrMissingProject
// 或 ErrMissingTitle。
func (s *Store) PutProject(ctx context.Context, p Project) error {
	if strings.TrimSpace(p.ID) == "" {
		return ErrMissingProject
	}
	if strings.TrimSpace(p.Title) == "" {
		return ErrMissingTitle
	}
	now := time.Now().UTC()
	if p.CreatedAt.IsZero() {
		p.CreatedAt = now
	}
	if p.UpdatedAt.IsZero() {
		p.UpdatedAt = now
	}
	_, err := s.db.ExecContext(ctx, `INSERT INTO project (id, title, desc, created_at, updated_at)
		VALUES (?, ?, ?, ?, ?)
		ON CONFLICT(id) DO UPDATE SET
			title = excluded.title,
			desc = excluded.desc,
			updated_at = excluded.updated_at`,
		p.ID, p.Title, p.Desc, formatTime(p.CreatedAt), formatTime(p.UpdatedAt))
	if err != nil {
		return fmt.Errorf("projectindex: upsert project: %w", err)
	}
	s.log.Debug("project upserted", "id", p.ID)
	return nil
}

// GetProject 返回给定 id 的项目。id 为空或
// 不存在时返回 ErrProjectNotFound。
func (s *Store) GetProject(ctx context.Context, id string) (*Project, error) {
	if strings.TrimSpace(id) == "" {
		return nil, ErrProjectNotFound
	}
	row := s.db.QueryRowContext(ctx, `SELECT id, title, desc, created_at, updated_at
		FROM project WHERE id = ?`, id)
	p, err := scanProject(row)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrProjectNotFound
	}
	if err != nil {
		return nil, fmt.Errorf("projectindex: get project: %w", err)
	}
	return p, nil
}

// DeleteProject 按 id 删除项目，并级联删除引用它的每个
// 章节。id 为空、或没有删除任何
// 项目行时返回 ErrProjectNotFound。删项目与删章节发生在
// 同一事务内，因此失败绝不会留下孤儿项目或章节。
func (s *Store) DeleteProject(ctx context.Context, id string) error {
	if strings.TrimSpace(id) == "" {
		return ErrProjectNotFound
	}
	tx, err := s.db.BeginTx(ctx, nil)
	if err != nil {
		return fmt.Errorf("projectindex: begin delete tx: %w", err)
	}
	defer func() { _ = tx.Rollback() }()

	res, err := tx.ExecContext(ctx, `DELETE FROM project_chapter WHERE project_id = ?`, id)
	if err != nil {
		return fmt.Errorf("projectindex: delete chapters: %w", err)
	}
	if _, err := res.RowsAffected(); err != nil {
		return fmt.Errorf("projectindex: delete chapters row count: %w", err)
	}

	res, err = tx.ExecContext(ctx, `DELETE FROM project WHERE id = ?`, id)
	if err != nil {
		return fmt.Errorf("projectindex: delete project: %w", err)
	}
	n, err := res.RowsAffected()
	if err != nil {
		return fmt.Errorf("projectindex: delete row count: %w", err)
	}
	if n == 0 {
		return ErrProjectNotFound
	}
	if err := tx.Commit(); err != nil {
		return fmt.Errorf("projectindex: commit delete tx: %w", err)
	}
	s.log.Debug("project deleted", "id", id)
	return nil
}

// scanProject 读取一行 project。
func scanProject(sc rowScanner) (*Project, error) {
	var (
		p                   Project
		createdAt, updatedAt string
	)
	if err := sc.Scan(&p.ID, &p.Title, &p.Desc, &createdAt, &updatedAt); err != nil {
		return nil, err
	}
	var err error
	if p.CreatedAt, err = parseTime(createdAt); err != nil {
		return nil, err
	}
	if p.UpdatedAt, err = parseTime(updatedAt); err != nil {
		return nil, err
	}
	return &p, nil
}

// newID 返回一个 128 位密码学随机 id，十六进制编码。它避开
// UUID 依赖，使本包保持自包含。rand.Read 只在
// 平台熵源损坏时失败，因此错误向上传播。
func newID() (string, error) {
	b := make([]byte, 16)
	if _, err := rand.Read(b); err != nil {
		return "", fmt.Errorf("projectindex: generate id: %w", err)
	}
	return hex.EncodeToString(b), nil
}