package history

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

// This file owns the single-message operations behind the Android collaboration batch
// ③a (D2 search, D3 edit/delete). Both are strictly session-scoped or id-scoped: a
// message is only ever reached through the session it belongs to (Search) or its own
// opaque id (UpdateMessage/DeleteMessage), so an isolated group/stranger session can
// never surface in another session's results (project red line).

// Search returns up to limit messages for sessionID whose content contains query,
// newest first. The match is a case-insensitive ASCII LIKE (SQLite's default for
// LIKE) with the query's %/_/\ escaped so they match literally; before is the same
// millisecond cursor as List (strictly older than before) and limit is clamped to
// [1, maxPageLimit]. rowid breaks created_at ties so same-millisecond messages keep a
// stable order. An empty query returns an empty (non-nil) slice — the caller uses
// List for plain paging instead. Search never crosses the session boundary.
func (s *Store) Search(ctx context.Context, sessionID, query string, before int64, limit int) ([]Message, error) {
	limit = clampLimit(limit)
	if query == "" {
		return make([]Message, 0), nil
	}
	sqlText := `SELECT id, session_id, role, content, mode, mood, image, thinking, platform, device_id, sender_name, adapter_id, created_at
		FROM chat_messages WHERE session_id = ? AND content LIKE ? ESCAPE '\'`
	args := []any{sessionID, "%" + escapeLike(query) + "%"}
	if before > 0 {
		sqlText += ` AND created_at < ?`
		args = append(args, before)
	}
	sqlText += ` ORDER BY created_at DESC, rowid DESC LIMIT ?`
	args = append(args, limit)

	rows, err := s.db.QueryContext(ctx, sqlText, args...)
	if err != nil {
		return nil, fmt.Errorf("history: search %s: %w", sessionID, err)
	}
	defer func() { _ = rows.Close() }()

	msgs := make([]Message, 0)
	for rows.Next() {
		m, err := scanMessage(rows)
		if err != nil {
			return nil, fmt.Errorf("history: scan search %s: %w", sessionID, err)
		}
		msgs = append(msgs, m)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("history: iterate search %s: %w", sessionID, err)
	}
	return msgs, nil
}

// UpdateMessage replaces the content of the message with id and returns the updated
// message (like AppendFull, so the caller can return/broadcast it without a second
// read). Only content changes; role, platform, timestamps and the rest stay as stored.
// An unknown id returns ErrMessageNotFound.
func (s *Store) UpdateMessage(ctx context.Context, id, content string) (Message, error) {
	res, err := s.db.ExecContext(ctx, `UPDATE chat_messages SET content = ? WHERE id = ?`, content, id)
	if err != nil {
		return Message{}, fmt.Errorf("history: update message %s: %w", id, err)
	}
	n, err := res.RowsAffected()
	if err != nil {
		return Message{}, fmt.Errorf("history: update message %s rows: %w", id, err)
	}
	if n == 0 {
		return Message{}, fmt.Errorf("history: update message %s: %w", id, ErrMessageNotFound)
	}
	return s.messageByID(ctx, id)
}

// DeleteMessage removes a single message. An unknown id returns ErrMessageNotFound.
func (s *Store) DeleteMessage(ctx context.Context, id string) error {
	res, err := s.db.ExecContext(ctx, `DELETE FROM chat_messages WHERE id = ?`, id)
	if err != nil {
		return fmt.Errorf("history: delete message %s: %w", id, err)
	}
	n, err := res.RowsAffected()
	if err != nil {
		return fmt.Errorf("history: delete message %s rows: %w", id, err)
	}
	if n == 0 {
		return fmt.Errorf("history: delete message %s: %w", id, ErrMessageNotFound)
	}
	return nil
}

// messageByID reads one message by id, returning ErrMessageNotFound when the row is
// absent.
func (s *Store) messageByID(ctx context.Context, id string) (Message, error) {
	row := s.db.QueryRowContext(ctx, `SELECT id, session_id, role, content, mode, mood, image, thinking, platform, device_id, sender_name, adapter_id, created_at
		FROM chat_messages WHERE id = ?`, id)
	m, err := scanMessage(row)
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return Message{}, fmt.Errorf("history: read message %s: %w", id, ErrMessageNotFound)
		}
		return Message{}, fmt.Errorf("history: read message %s: %w", id, err)
	}
	return m, nil
}

// escapeLike escapes the LIKE wildcards in a user query so %, _ and \ match literally
// (the caller pairs it with ESCAPE '\'). It is applied before the %...% wrapping.
func escapeLike(query string) string {
	return strings.NewReplacer(`\`, `\\`, `%`, `\%`, `_`, `\_`).Replace(query)
}