package db

import (
	"strings"
	"time"
)

// GetRepositoryAnnotations retrieves all annotations for a repository
func GetRepositoryAnnotations(db DBTX, did, repository string) (map[string]string, error) {
	rows, err := db.Query(`
		SELECT key, value
		FROM repository_annotations
		WHERE did = ? AND repository = ?
	`, did, repository)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	annotations := make(map[string]string)
	for rows.Next() {
		var key, value string
		if err := rows.Scan(&key, &value); err != nil {
			return nil, err
		}
		annotations[key] = value
	}

	return annotations, rows.Err()
}

// UpsertRepositoryAnnotations upserts annotations for a repository.
// Stale keys not present in the new map are deleted.
// Unchanged values are skipped to avoid unnecessary writes.
// Only called when manifest has at least one non-empty annotation.
// Atomicity is provided by the caller's transaction when used during backfill.
func UpsertRepositoryAnnotations(db DBTX, did, repository string, annotations map[string]string) error {
	// Delete keys that are no longer in the annotation set
	if len(annotations) == 0 {
		_, err := db.Exec(`
			DELETE FROM repository_annotations
			WHERE did = ? AND repository = ?
		`, did, repository)
		return err
	}

	// Build placeholders for the NOT IN clause
	placeholders := make([]string, 0, len(annotations))
	args := []any{did, repository}
	for key := range annotations {
		placeholders = append(placeholders, "?")
		args = append(args, key)
	}
	_, err := db.Exec(`
		DELETE FROM repository_annotations
		WHERE did = ? AND repository = ? AND key NOT IN (`+strings.Join(placeholders, ",")+`)
	`, args...)
	if err != nil {
		return err
	}

	// Upsert each annotation, only writing when value changed
	stmt, err := db.Prepare(`
		INSERT INTO repository_annotations (did, repository, key, value, updated_at)
		VALUES (?, ?, ?, ?, ?)
		ON CONFLICT(did, repository, key) DO UPDATE SET
			value = excluded.value,
			updated_at = excluded.updated_at
		WHERE excluded.value != repository_annotations.value
	`)
	if err != nil {
		return err
	}
	defer stmt.Close()

	now := time.Now()
	for key, value := range annotations {
		_, err = stmt.Exec(did, repository, key, value, now)
		if err != nil {
			return err
		}
	}

	return nil
}

// DeleteRepositoryAnnotations removes all annotations for a repository
func DeleteRepositoryAnnotations(db DBTX, did, repository string) error {
	_, err := db.Exec(`
		DELETE FROM repository_annotations
		WHERE did = ? AND repository = ?
	`, did, repository)
	return err
}