// Package testsupport wires tests to a real PostgreSQL database.
//
// Isolation strategy: every test gets its own freshly created tenant. Because
// the whole application is tenant-scoped by design, a per-test tenant gives
// each test a private world without truncating tables between runs -- and it
// exercises the tenant scoping on every single query rather than trusting it.
//
// Set TEST_DATABASE_URL to point at a throwaway database. The default assumes
// a local "travelhub_test". The schema is applied automatically on first use.
package testsupport

import (
	"context"
	"fmt"
	"net/url"
	"os"
	"path/filepath"
	"runtime"
	"sync"
	"testing"
	"time"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5/pgxpool"
	"golang.org/x/crypto/bcrypt"

	"github.com/travelswitch/travelhub/backend/internal/config"
	"github.com/travelswitch/travelhub/backend/internal/models"
	"github.com/travelswitch/travelhub/backend/internal/repository"
)

// Password is the plaintext behind every user created by this package.
const Password = "testpass123"

var (
	poolOnce sync.Once
	pool     *pgxpool.Pool
	poolErr  error
)

// Fixture is one test's private slice of the world.
type Fixture struct {
	Pool   *pgxpool.Pool
	Repo   *repository.Repository
	Tenant models.Tenant
	Admin  models.User
	Agent  models.User
}

// Setup returns a Fixture backed by a brand-new tenant. The tenant and
// everything that cascades from it are removed when the test finishes.
func Setup(t *testing.T) *Fixture {
	t.Helper()

	p := sharedPool(t)
	ctx := context.Background()

	slug := "test-" + uuid.NewString()[:8]

	var tenant models.Tenant
	err := p.QueryRow(ctx,
		`INSERT INTO tenants (slug, name) VALUES ($1, $2)
		 RETURNING id, slug, name, status, created_at`,
		slug, "Test Agency "+slug,
	).Scan(&tenant.ID, &tenant.Slug, &tenant.Name, &tenant.Status, &tenant.CreatedAt)
	if err != nil {
		t.Fatalf("create tenant: %v", err)
	}

	t.Cleanup(func() {
		// ON DELETE CASCADE clears users, flights, bookings and passengers.
		if _, err := p.Exec(context.Background(),
			`DELETE FROM tenants WHERE id = $1`, tenant.ID); err != nil {
			t.Logf("cleanup tenant %s: %v", tenant.Slug, err)
		}
	})

	f := &Fixture{Pool: p, Repo: repository.New(p), Tenant: tenant}
	f.Admin = f.NewUser(t, "admin@"+slug+".test", "admin")
	f.Agent = f.NewUser(t, "agent@"+slug+".test", "agent")
	return f
}

// NewUser adds a user to the fixture's tenant.
func (f *Fixture) NewUser(t *testing.T, email, role string) models.User {
	t.Helper()

	// MinCost keeps the suite fast; the middleware verifies any cost.
	hash, err := bcrypt.GenerateFromPassword([]byte(Password), bcrypt.MinCost)
	if err != nil {
		t.Fatalf("hash password: %v", err)
	}

	var u models.User
	err = f.Pool.QueryRow(context.Background(),
		`INSERT INTO users (tenant_id, email, password_hash, full_name, role)
		 VALUES ($1, $2, $3, $4, $5)
		 RETURNING id, tenant_id, email, password_hash, full_name, role, created_at`,
		f.Tenant.ID, email, string(hash), "Test "+role, role,
	).Scan(&u.ID, &u.TenantID, &u.Email, &u.PasswordHash, &u.FullName, &u.Role, &u.CreatedAt)
	if err != nil {
		t.Fatalf("create user %s: %v", email, err)
	}
	return u
}

// FlightOpts describes a flight to insert. Zero values get sensible defaults.
type FlightOpts struct {
	Number      string
	Origin      string // IATA, default JFK
	Destination string // IATA, default LHR
	DepartsIn   time.Duration
	Duration    time.Duration
	Cabin       string
	Price       float64
	Seats       int
	Available   *int // defaults to Seats
	Status      string
}

// NewFlight inserts one flight into the fixture's tenant and returns it.
func (f *Fixture) NewFlight(t *testing.T, opts FlightOpts) models.Flight {
	t.Helper()
	ctx := context.Background()

	if opts.Number == "" {
		opts.Number = "TT" + uuid.NewString()[:4]
	}
	if opts.Origin == "" {
		opts.Origin = "JFK"
	}
	if opts.Destination == "" {
		opts.Destination = "LHR"
	}
	if opts.DepartsIn == 0 {
		opts.DepartsIn = 48 * time.Hour
	}
	if opts.Duration == 0 {
		opts.Duration = 7 * time.Hour
	}
	if opts.Cabin == "" {
		opts.Cabin = "economy"
	}
	if opts.Price == 0 {
		opts.Price = 500
	}
	if opts.Seats == 0 {
		opts.Seats = 100
	}
	if opts.Status == "" {
		opts.Status = "scheduled"
	}
	available := opts.Seats
	if opts.Available != nil {
		available = *opts.Available
	}

	departs := time.Now().Add(opts.DepartsIn)

	var id uuid.UUID
	err := f.Pool.QueryRow(ctx,
		`INSERT INTO flights (tenant_id, airline_id, flight_number,
		                      origin_airport_id, destination_airport_id,
		                      departure_time, arrival_time, aircraft, cabin_class,
		                      base_price, currency, seats_total, seats_available, status)
		 VALUES ($1,
		         (SELECT id FROM airlines WHERE iata_code = 'AA'),
		         $2,
		         (SELECT id FROM airports WHERE iata_code = $3),
		         (SELECT id FROM airports WHERE iata_code = $4),
		         $5, $6, 'Boeing 787-9', $7, $8, 'USD', $9, $10, $11)
		 RETURNING id`,
		f.Tenant.ID, opts.Number, opts.Origin, opts.Destination,
		departs, departs.Add(opts.Duration), opts.Cabin, opts.Price,
		opts.Seats, available, opts.Status,
	).Scan(&id)
	if err != nil {
		t.Fatalf("create flight: %v", err)
	}

	flight, err := f.Repo.FlightByID(ctx, f.Tenant.ID, id)
	if err != nil {
		t.Fatalf("read back flight: %v", err)
	}
	return flight
}

// SeatsAvailable reads the current availability straight from the row, for
// assertions about seat accounting.
func (f *Fixture) SeatsAvailable(t *testing.T, flightID uuid.UUID) int {
	t.Helper()

	var seats int
	err := f.Pool.QueryRow(context.Background(),
		`SELECT seats_available FROM flights WHERE id = $1`, flightID).Scan(&seats)
	if err != nil {
		t.Fatalf("read seats: %v", err)
	}
	return seats
}

// Suspend flips the tenant to suspended, for tests that check sign-in is
// refused afterwards.
func (f *Fixture) Suspend(t *testing.T) {
	t.Helper()

	if _, err := f.Pool.Exec(context.Background(),
		`UPDATE tenants SET status = 'suspended' WHERE id = $1`, f.Tenant.ID); err != nil {
		t.Fatalf("suspend tenant: %v", err)
	}
}

// sharedPool opens the pool once per test binary and prepares the schema.
func sharedPool(t *testing.T) *pgxpool.Pool {
	t.Helper()

	poolOnce.Do(func() {
		// Pick up backend/.env so a developer who configured the app can run
		// the tests without setting anything extra.
		config.LoadDotEnv()

		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
		defer cancel()

		p, err := pgxpool.New(ctx, databaseURL())
		if err != nil {
			poolErr = fmt.Errorf("open test pool: %w", err)
			return
		}
		if err := p.Ping(ctx); err != nil {
			poolErr = fmt.Errorf("ping test database: %w", err)
			return
		}
		if err := applySchema(ctx, p); err != nil {
			poolErr = err
			return
		}
		if err := seedReference(ctx, p); err != nil {
			poolErr = err
			return
		}
		pool = p
	})

	if poolErr != nil {
		t.Fatalf("test database unavailable: %v\n"+
			"Set TEST_DATABASE_URL, or create the default database with:\n"+
			"  createdb -U postgres travelhub_test", poolErr)
	}
	return pool
}

// databaseURL resolves the test DSN, preferring TEST_DATABASE_URL and
// otherwise assembling one from the same DB_* variables the app uses, with the
// database name swapped for the test one.
func databaseURL() string {
	if raw := os.Getenv("TEST_DATABASE_URL"); raw != "" {
		return raw
	}

	user := envOr("DB_USER", "postgres")
	pass := envOr("DB_PASSWORD", "postgres")
	host := envOr("DB_HOST", "localhost")
	port := envOr("DB_PORT", "5432")
	name := envOr("TEST_DB_NAME", "travelhub_test")

	u := &url.URL{
		Scheme:   "postgres",
		User:     url.UserPassword(user, pass),
		Host:     host + ":" + port,
		Path:     "/" + name,
		RawQuery: "sslmode=disable",
	}
	return u.String()
}

func envOr(key, fallback string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return fallback
}

// applySchema runs 001_init.sql, which is written to be re-runnable.
func applySchema(ctx context.Context, p *pgxpool.Pool) error {
	path := filepath.Join(moduleRoot(), "migrations", "001_init.sql")
	sql, err := os.ReadFile(path)
	if err != nil {
		return fmt.Errorf("read schema %s: %w", path, err)
	}
	// Exec with no arguments uses the simple protocol, which accepts a script
	// of several statements.
	if _, err := p.Exec(ctx, string(sql)); err != nil {
		return fmt.Errorf("apply schema: %w", err)
	}
	return nil
}

// seedReference inserts the global airports and airlines the fixtures need.
func seedReference(ctx context.Context, p *pgxpool.Pool) error {
	const sql = `
		INSERT INTO airports (iata_code, name, city, country, timezone) VALUES
			('JFK', 'John F. Kennedy International', 'New York',    'United States',  'America/New_York'),
			('LHR', 'Heathrow',                      'London',      'United Kingdom', 'Europe/London'),
			('LAX', 'Los Angeles International',     'Los Angeles', 'United States',  'America/Los_Angeles'),
			('DXB', 'Dubai International',           'Dubai',       'United Arab Emirates', 'Asia/Dubai')
		ON CONFLICT (iata_code) DO NOTHING;

		INSERT INTO airlines (iata_code, name) VALUES
			('AA', 'American Airlines'),
			('BA', 'British Airways')
		ON CONFLICT (iata_code) DO NOTHING;`

	if _, err := p.Exec(ctx, sql); err != nil {
		return fmt.Errorf("seed reference data: %w", err)
	}
	return nil
}

// moduleRoot locates backend/ from this file's compile-time path, so tests can
// find migrations no matter which package directory they run from.
func moduleRoot() string {
	_, thisFile, _, ok := runtime.Caller(0)
	if !ok {
		return "."
	}
	// .../backend/internal/testsupport/testsupport.go -> .../backend
	return filepath.Dir(filepath.Dir(filepath.Dir(thisFile)))
}