package diunwebhook

import (
	"database/sql"
	"time"
)

// PostgresStore implements Store using a PostgreSQL database.
type PostgresStore struct {
	db *sql.DB
}

// NewPostgresStore creates a new PostgresStore backed by the given *sql.DB.
// Configures connection pool settings appropriate for PostgreSQL.
// PostgreSQL handles concurrent writes natively so no mutex is needed.
func NewPostgresStore(db *sql.DB) *PostgresStore {
	db.SetMaxOpenConns(25)
	db.SetMaxIdleConns(5)
	db.SetConnMaxLifetime(5 * time.Minute)
	return &PostgresStore{db: db}
}

// UpsertEvent inserts or updates a DIUN event in the updates table.
// On conflict (same image), all fields are updated and acknowledged_at is reset to NULL.
func (s *PostgresStore) UpsertEvent(event DiunEvent) error {
	_, err := s.db.Exec(`
		INSERT INTO updates (
			image, diun_version, hostname, status, provider,
			hub_link, mime_type, digest, created, platform,
			ctn_name, ctn_id, ctn_state, ctn_status,
			received_at, acknowledged_at
		) VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15,NULL)
		ON CONFLICT(image) DO UPDATE SET
			diun_version    = EXCLUDED.diun_version,
			hostname        = EXCLUDED.hostname,
			status          = EXCLUDED.status,
			provider        = EXCLUDED.provider,
			hub_link        = EXCLUDED.hub_link,
			mime_type       = EXCLUDED.mime_type,
			digest          = EXCLUDED.digest,
			created         = EXCLUDED.created,
			platform        = EXCLUDED.platform,
			ctn_name        = EXCLUDED.ctn_name,
			ctn_id          = EXCLUDED.ctn_id,
			ctn_state       = EXCLUDED.ctn_state,
			ctn_status      = EXCLUDED.ctn_status,
			received_at     = EXCLUDED.received_at,
			acknowledged_at = NULL`,
		event.Image, event.DiunVersion, event.Hostname, event.Status, event.Provider,
		event.HubLink, event.MimeType, event.Digest,
		event.Created.Format(time.RFC3339), event.Platform,
		event.Metadata.ContainerName, event.Metadata.ContainerID,
		event.Metadata.State, event.Metadata.Status,
		time.Now().Format(time.RFC3339),
	)
	return err
}

// GetUpdates returns all update entries joined with their tag assignments.
func (s *PostgresStore) GetUpdates() (map[string]UpdateEntry, error) {
	rows, err := s.db.Query(`SELECT u.image, u.diun_version, u.hostname, u.status, u.provider,
		u.hub_link, u.mime_type, u.digest, u.created, u.platform,
		u.ctn_name, u.ctn_id, u.ctn_state, u.ctn_status, u.received_at, COALESCE(u.acknowledged_at, ''),
		t.id, t.name
		FROM updates u
		LEFT JOIN tag_assignments ta ON u.image = ta.image
		LEFT JOIN tags t             ON ta.tag_id = t.id`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	result := make(map[string]UpdateEntry)
	for rows.Next() {
		var e UpdateEntry
		var createdStr, receivedStr, acknowledgedAt string
		var tagID sql.NullInt64
		var tagName sql.NullString
		err := rows.Scan(&e.Event.Image, &e.Event.DiunVersion, &e.Event.Hostname,
			&e.Event.Status, &e.Event.Provider, &e.Event.HubLink, &e.Event.MimeType,
			&e.Event.Digest, &createdStr, &e.Event.Platform,
			&e.Event.Metadata.ContainerName, &e.Event.Metadata.ContainerID,
			&e.Event.Metadata.State, &e.Event.Metadata.Status,
			&receivedStr, &acknowledgedAt, &tagID, &tagName)
		if err != nil {
			return nil, err
		}
		e.Event.Created, _ = time.Parse(time.RFC3339, createdStr)
		e.ReceivedAt, _ = time.Parse(time.RFC3339, receivedStr)
		e.Acknowledged = acknowledgedAt != ""
		if tagID.Valid && tagName.Valid {
			e.Tag = &Tag{ID: int(tagID.Int64), Name: tagName.String}
		}
		result[e.Event.Image] = e
	}
	return result, rows.Err()
}

// AcknowledgeUpdate marks the given image as acknowledged.
// Returns found=false if no row with that image exists.
func (s *PostgresStore) AcknowledgeUpdate(image string) (found bool, err error) {
	res, err := s.db.Exec(`UPDATE updates SET acknowledged_at = NOW() WHERE image = $1`, image)
	if err != nil {
		return false, err
	}
	n, _ := res.RowsAffected()
	return n > 0, nil
}

// ListTags returns all tags ordered by name.
func (s *PostgresStore) ListTags() ([]Tag, error) {
	rows, err := s.db.Query(`SELECT id, name FROM tags ORDER BY name`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	tags := []Tag{}
	for rows.Next() {
		var t Tag
		if err := rows.Scan(&t.ID, &t.Name); err != nil {
			return nil, err
		}
		tags = append(tags, t)
	}
	return tags, rows.Err()
}

// CreateTag inserts a new tag with the given name and returns the created tag.
// Uses RETURNING id since pgx does not support LastInsertId.
func (s *PostgresStore) CreateTag(name string) (Tag, error) {
	var id int
	err := s.db.QueryRow(
		`INSERT INTO tags (name) VALUES ($1) RETURNING id`, name,
	).Scan(&id)
	if err != nil {
		return Tag{}, err
	}
	return Tag{ID: id, Name: name}, nil
}

// DeleteTag deletes the tag with the given id.
// Returns found=false if no tag with that id exists.
func (s *PostgresStore) DeleteTag(id int) (found bool, err error) {
	res, err := s.db.Exec(`DELETE FROM tags WHERE id = $1`, id)
	if err != nil {
		return false, err
	}
	n, _ := res.RowsAffected()
	return n > 0, nil
}

// AssignTag assigns the given image to the given tag.
// Uses INSERT ... ON CONFLICT DO UPDATE so re-assigning an image to a different tag replaces the existing assignment.
func (s *PostgresStore) AssignTag(image string, tagID int) error {
	_, err := s.db.Exec(
		`INSERT INTO tag_assignments (image, tag_id) VALUES ($1, $2)
		 ON CONFLICT (image) DO UPDATE SET tag_id = EXCLUDED.tag_id`,
		image, tagID,
	)
	return err
}

// UnassignTag removes any tag assignment for the given image.
func (s *PostgresStore) UnassignTag(image string) error {
	_, err := s.db.Exec(`DELETE FROM tag_assignments WHERE image = $1`, image)
	return err
}

// TagExists returns true if a tag with the given id exists.
func (s *PostgresStore) TagExists(id int) (bool, error) {
	var count int
	err := s.db.QueryRow(`SELECT COUNT(*) FROM tags WHERE id = $1`, id).Scan(&count)
	if err != nil {
		return false, err
	}
	return count > 0, nil
}