// Package postgres provides PostgreSQL-based implementations of port interfaces.
package postgres

import (
	"context"
	"database/sql"
	"encoding/json"
	"fmt"
	"time"

	"github.com/orchard9/rdev/internal/domain"
	"github.com/orchard9/rdev/internal/port"
)

// BuildAuditRepository implements port.BuildAudit using PostgreSQL.
type BuildAuditRepository struct {
	db *sql.DB
}

// NewBuildAuditRepository creates a new PostgreSQL build audit repository.
func NewBuildAuditRepository(db *sql.DB) *BuildAuditRepository {
	return &BuildAuditRepository{db: db}
}

// Ensure BuildAuditRepository implements port.BuildAudit at compile time.
var _ port.BuildAudit = (*BuildAuditRepository)(nil)

// Record creates a new audit entry when a build starts.
func (r *BuildAuditRepository) Record(ctx context.Context, entry *domain.BuildAuditEntry) error {
	specJSON, err := json.Marshal(entry.Spec)
	if err != nil {
		return fmt.Errorf("marshal build spec: %w", err)
	}

	_, err = r.db.ExecContext(ctx, `
		INSERT INTO build_audit (task_id, project_id, worker_id, spec, status, started_at)
		VALUES ($1, $2, $3, $4, $5, $6)
	`, entry.TaskID, entry.ProjectID, nullString(entry.WorkerID),
		specJSON, entry.Status, entry.StartedAt)

	if err != nil {
		return fmt.Errorf("record build audit: %w", err)
	}

	return nil
}

// Update modifies an existing entry when a build completes.
func (r *BuildAuditRepository) Update(ctx context.Context, taskID string, result *domain.BuildResult) error {
	var resultJSON []byte
	var err error

	if result != nil {
		resultJSON, err = json.Marshal(result)
		if err != nil {
			return fmt.Errorf("marshal build result: %w", err)
		}
	}

	status := domain.BuildStatusCompleted
	if result != nil && !result.Success {
		status = domain.BuildStatusFailed
	}

	now := time.Now()
	res, err := r.db.ExecContext(ctx, `
		UPDATE build_audit
		SET result = $2, status = $3, completed_at = $4
		WHERE task_id = $1
	`, taskID, resultJSON, status, now)
	if err != nil {
		return fmt.Errorf("update build audit: %w", err)
	}

	rows, err := res.RowsAffected()
	if err != nil {
		return fmt.Errorf("rows affected: %w", err)
	}
	if rows == 0 {
		return domain.ErrBuildNotFound
	}

	return nil
}

// UpdateStatus updates the status and worker assignment when a task is claimed.
// When status is "running" (task claimed for execution/retry), this also clears
// any stale result and completed_at from previous failed attempts.
func (r *BuildAuditRepository) UpdateStatus(ctx context.Context, taskID string, status domain.BuildStatus, workerID string) error {
	// When a task transitions to running (claimed for execution or retry),
	// clear stale result data from any previous failed attempts.
	var query string
	if status == domain.BuildStatusRunning {
		query = `
			UPDATE build_audit
			SET status = $2, worker_id = $3, result = NULL, completed_at = NULL, started_at = NOW()
			WHERE task_id = $1
		`
	} else {
		query = `
			UPDATE build_audit
			SET status = $2, worker_id = $3
			WHERE task_id = $1
		`
	}

	res, err := r.db.ExecContext(ctx, query, taskID, status, nullString(workerID))
	if err != nil {
		return fmt.Errorf("update build audit status: %w", err)
	}

	rows, err := res.RowsAffected()
	if err != nil {
		return fmt.Errorf("rows affected: %w", err)
	}
	if rows == 0 {
		return domain.ErrBuildNotFound
	}

	return nil
}

// Get retrieves a specific audit entry by task ID.
func (r *BuildAuditRepository) Get(ctx context.Context, taskID string) (*domain.BuildAuditEntry, error) {
	rows, err := r.db.QueryContext(ctx, `
		SELECT task_id, project_id, worker_id, spec, result, status,
		       started_at, completed_at
		FROM build_audit
		WHERE task_id = $1
	`, taskID)
	if err != nil {
		return nil, fmt.Errorf("get build audit: %w", err)
	}
	defer func() { _ = rows.Close() }()

	if !rows.Next() {
		if err := rows.Err(); err != nil {
			return nil, fmt.Errorf("get build audit: %w", err)
		}
		return nil, domain.ErrBuildNotFound
	}
	return r.scanEntry(rows)
}

// List returns audit entries matching the filter.
func (r *BuildAuditRepository) List(ctx context.Context, filter port.BuildAuditFilter) ([]*domain.BuildAuditEntry, error) {
	query := `
		SELECT task_id, project_id, worker_id, spec, result, status,
		       started_at, completed_at
		FROM build_audit
		WHERE 1=1`
	args := []any{}
	argNum := 1

	if filter.ProjectID != "" {
		query += fmt.Sprintf(" AND project_id = $%d", argNum)
		args = append(args, filter.ProjectID)
		argNum++
	}

	if filter.WorkerID != "" {
		query += fmt.Sprintf(" AND worker_id = $%d", argNum)
		args = append(args, filter.WorkerID)
		argNum++
	}

	if filter.Status != nil {
		query += fmt.Sprintf(" AND status = $%d", argNum)
		args = append(args, string(*filter.Status))
		argNum++
	}

	if !filter.Since.IsZero() {
		query += fmt.Sprintf(" AND started_at >= $%d", argNum)
		args = append(args, filter.Since)
		argNum++
	}

	query += " ORDER BY started_at DESC"

	if filter.Limit > 0 {
		query += fmt.Sprintf(" LIMIT $%d", argNum)
		args = append(args, filter.Limit)
	}

	rows, err := r.db.QueryContext(ctx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("list build audit: %w", err)
	}
	defer func() { _ = rows.Close() }()

	var entries []*domain.BuildAuditEntry
	for rows.Next() {
		entry, err := r.scanEntry(rows)
		if err != nil {
			return nil, err
		}
		entries = append(entries, entry)
	}

	return entries, rows.Err()
}

// scanEntry scans a single build audit row from a query result.
func (r *BuildAuditRepository) scanEntry(rows *sql.Rows) (*domain.BuildAuditEntry, error) {
	var entry domain.BuildAuditEntry
	var workerID sql.NullString
	var specJSON []byte
	var resultJSON []byte
	var completedAt sql.NullTime

	err := rows.Scan(
		&entry.TaskID,
		&entry.ProjectID,
		&workerID,
		&specJSON,
		&resultJSON,
		&entry.Status,
		&entry.StartedAt,
		&completedAt,
	)
	if err != nil {
		return nil, fmt.Errorf("scan build audit: %w", err)
	}

	if workerID.Valid {
		entry.WorkerID = workerID.String
	}
	if completedAt.Valid {
		entry.CompletedAt = &completedAt.Time
	}

	if len(specJSON) > 0 {
		if err := json.Unmarshal(specJSON, &entry.Spec); err != nil {
			return nil, fmt.Errorf("unmarshal build spec: %w", err)
		}
	}

	if len(resultJSON) > 0 {
		entry.Result = &domain.BuildResult{}
		if err := json.Unmarshal(resultJSON, entry.Result); err != nil {
			return nil, fmt.Errorf("unmarshal build result: %w", err)
		}
	}

	return &entry, nil
}