// Package database provides a standardized database connection pool.
//
// Production uses CockroachDB (provisioned by the platform).
// Local development uses PostgreSQL via docker-compose.
// Both are wire-compatible and use the lib/pq driver ("postgres").
//
// This package wraps sqlx to provide:
//   - Connection pool management with sensible defaults
//   - Health checks for liveness/readiness probes
//   - Context-aware query execution
//
// Usage:
//
//	// Connect with configuration from pkg/config
//	dbCfg := config.ReadDatabaseConfig()
//	pool, err := database.Connect(ctx, dbCfg.URL, database.Options{
//	    MaxOpenConns:    dbCfg.MaxOpenConns,
//	    MaxIdleConns:    dbCfg.MaxIdleConns,
//	    ConnMaxLifetime: dbCfg.ConnMaxLifetime,
//	})
//	if err != nil {
//	    log.Fatal("failed to connect to database", "error", err)
//	}
//	defer pool.Close()
//
//	// Use pool.DB for queries
//	var users []User
//	err = pool.DB.SelectContext(ctx, &users, "SELECT * FROM users")
package database

import (
	"context"
	"fmt"
	"net/url"
	"time"

	"github.com/jmoiron/sqlx"
	_ "github.com/lib/pq" // PostgreSQL-compatible driver (works with both PostgreSQL and CockroachDB)
)

// Pool wraps a sqlx.DB with additional lifecycle management.
type Pool struct {
	// DB is the underlying sqlx database connection pool.
	// Use this for all query operations.
	DB *sqlx.DB

	// URL is the connection URL (redacted for logging).
	URL string
}

// Options configures the database connection pool.
type Options struct {
	// MaxOpenConns sets the maximum number of open connections.
	// Default: 25
	MaxOpenConns int

	// MaxIdleConns sets the maximum number of idle connections.
	// Default: 5
	MaxIdleConns int

	// ConnMaxLifetime sets the maximum lifetime of a connection.
	// Default: 5 minutes
	ConnMaxLifetime time.Duration

	// ConnMaxIdleTime sets the maximum idle time for a connection.
	// Default: 0 (no limit)
	ConnMaxIdleTime time.Duration
}

// Connect establishes a connection pool to the database.
// The URL should be a PostgreSQL-compatible connection string (works with CockroachDB):
//
//	postgres://user:pass@host:port/dbname?sslmode=disable
func Connect(ctx context.Context, url string, opts Options) (*Pool, error) {
	if url == "" {
		return nil, fmt.Errorf("database URL is required")
	}

	// Apply defaults
	if opts.MaxOpenConns == 0 {
		opts.MaxOpenConns = 25
	}
	if opts.MaxIdleConns == 0 {
		opts.MaxIdleConns = 5
	}
	if opts.ConnMaxLifetime == 0 {
		opts.ConnMaxLifetime = 5 * time.Minute
	}

	db, err := sqlx.ConnectContext(ctx, "postgres", url)
	if err != nil {
		return nil, fmt.Errorf("failed to connect to database: %w", err)
	}

	// Configure pool
	db.SetMaxOpenConns(opts.MaxOpenConns)
	db.SetMaxIdleConns(opts.MaxIdleConns)
	db.SetConnMaxLifetime(opts.ConnMaxLifetime)
	if opts.ConnMaxIdleTime > 0 {
		db.SetConnMaxIdleTime(opts.ConnMaxIdleTime)
	}

	// Verify connection
	if err := db.PingContext(ctx); err != nil {
		db.Close()
		return nil, fmt.Errorf("failed to ping database: %w", err)
	}

	return &Pool{
		DB:  db,
		URL: redactURL(url),
	}, nil
}

// MustConnect is like Connect but panics on error.
// Useful in main() for fail-fast initialization.
func MustConnect(ctx context.Context, url string, opts Options) *Pool {
	pool, err := Connect(ctx, url, opts)
	if err != nil {
		panic(fmt.Sprintf("failed to connect to database: %v", err))
	}
	return pool
}

// Close closes the database connection pool.
func (p *Pool) Close() error {
	if p.DB != nil {
		return p.DB.Close()
	}
	return nil
}

// Ping verifies the database connection is alive.
// Use this for health checks.
func (p *Pool) Ping(ctx context.Context) error {
	return p.DB.PingContext(ctx)
}

// Stats returns connection pool statistics.
func (p *Pool) Stats() Stats {
	s := p.DB.Stats()
	return Stats{
		MaxOpenConnections: s.MaxOpenConnections,
		OpenConnections:    s.OpenConnections,
		InUse:              s.InUse,
		Idle:               s.Idle,
		WaitCount:          s.WaitCount,
		WaitDuration:       s.WaitDuration,
	}
}

// Stats holds connection pool statistics.
type Stats struct {
	MaxOpenConnections int
	OpenConnections    int
	InUse              int
	Idle               int
	WaitCount          int64
	WaitDuration       time.Duration
}

// redactURL removes password from database URL for safe logging.
func redactURL(rawURL string) string {
	u, err := url.Parse(rawURL)
	if err != nil {
		return "[invalid-url]"
	}
	if u.User != nil {
		u.User = url.UserPassword(u.User.Username(), "****")
	}
	return u.String()
}