package db

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

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
)

type User struct {
	ID            uuid.UUID  `json:"id"`
	Email         string     `json:"email"`
	Name          *string    `json:"name,omitempty"`
	PasswordHash  *string    `json:"-"`
	EmailVerified bool       `json:"email_verified"`
	Provider      string     `json:"provider"`
	ProviderID    *string    `json:"provider_id,omitempty"`
	CreatedAt     time.Time  `json:"created_at"`
	UpdatedAt     time.Time  `json:"updated_at"`
	LastLoginAt   *time.Time `json:"last_login_at,omitempty"`
}

type MagicLink struct {
	Token     string    `json:"token"`
	UserID    uuid.UUID `json:"user_id"`
	Email     string    `json:"email"`
	Used      bool      `json:"used"`
	ExpiresAt time.Time `json:"expires_at"`
	CreatedAt time.Time `json:"created_at"`
}

func (db *DB) GetUserByEmail(ctx context.Context, email string) (*User, error) {
	var user User
	var name, passwordHash, providerID *string
	var lastLoginAt *time.Time

	err := db.QueryRow(ctx, `
		SELECT id, email, name, password_hash, email_verified, provider, provider_id, created_at, updated_at, last_login_at
		FROM users 
		WHERE email = $1
	`, email).Scan(
		&user.ID, &user.Email, &name, &passwordHash,
		&user.EmailVerified, &user.Provider, &providerID,
		&user.CreatedAt, &user.UpdatedAt, &lastLoginAt,
	)
	if err == pgx.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}

	user.Name = name
	user.PasswordHash = passwordHash
	user.ProviderID = providerID
	user.LastLoginAt = lastLoginAt
	return &user, nil
}

func (db *DB) GetUserByID(ctx context.Context, id uuid.UUID) (*User, error) {
	var user User
	var name, passwordHash, providerID *string
	var lastLoginAt *time.Time

	err := db.QueryRow(ctx, `
		SELECT id, email, name, password_hash, email_verified, provider, provider_id, created_at, updated_at, last_login_at
		FROM users 
		WHERE id = $1
	`, id).Scan(
		&user.ID, &user.Email, &name, &passwordHash,
		&user.EmailVerified, &user.Provider, &providerID,
		&user.CreatedAt, &user.UpdatedAt, &lastLoginAt,
	)
	if err == pgx.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}

	user.Name = name
	user.PasswordHash = passwordHash
	user.ProviderID = providerID
	user.LastLoginAt = lastLoginAt
	return &user, nil
}

func (db *DB) GetUserByProviderID(ctx context.Context, provider, providerID string) (*User, error) {
	var user User
	var name, passwordHash *string
	var lastLoginAt *time.Time

	err := db.QueryRow(ctx, `
		SELECT id, email, name, password_hash, email_verified, provider, provider_id, created_at, updated_at, last_login_at
		FROM users 
		WHERE provider = $1 AND provider_id = $2
	`, provider, providerID).Scan(
		&user.ID, &user.Email, &name, &passwordHash,
		&user.EmailVerified, &user.Provider, &user.ProviderID,
		&user.CreatedAt, &user.UpdatedAt, &lastLoginAt,
	)
	if err == pgx.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}

	user.Name = name
	user.PasswordHash = passwordHash
	user.LastLoginAt = lastLoginAt
	return &user, nil
}

func (db *DB) CreateUser(ctx context.Context, user *User) (*User, error) {
	if user.ID == uuid.Nil {
		user.ID = uuid.Must(uuid.NewV7())
	}
	now := time.Now()
	user.CreatedAt = now
	user.UpdatedAt = now

	_, err := db.pool.Exec(ctx, `
		INSERT INTO users (id, email, name, password_hash, email_verified, provider, provider_id, created_at, updated_at)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $8)
	`, user.ID, user.Email, user.Name, user.PasswordHash, user.EmailVerified, user.Provider, user.ProviderID, now)

	if err != nil {
		return nil, fmt.Errorf("create user: %w", err)
	}

	return user, nil
}

func (db *DB) UpdateUser(ctx context.Context, user *User) error {
	user.UpdatedAt = time.Now()

	_, err := db.pool.Exec(ctx, `
		UPDATE users 
		SET email = $2, name = $3, password_hash = $4, email_verified = $5, 
		    provider = $6, provider_id = $7, updated_at = $8, last_login_at = $9
		WHERE id = $1
	`, user.ID, user.Email, user.Name, user.PasswordHash, user.EmailVerified,
		user.Provider, user.ProviderID, user.UpdatedAt, user.LastLoginAt)

	return err
}

func (db *DB) UpdateLastLogin(ctx context.Context, userID uuid.UUID) error {
	_, err := db.pool.Exec(ctx, `
		UPDATE users SET last_login_at = NOW(), updated_at = NOW() WHERE id = $1
	`, userID)
	return err
}

func (db *DB) CreateMagicLink(ctx context.Context, token string, email string, userID uuid.UUID, expiresAt time.Time) error {
	_, err := db.pool.Exec(ctx, `
		INSERT INTO magic_links (token, user_id, email, expires_at, created_at)
		VALUES ($1, $2, $3, $4, NOW())
	`, token, userID, email, expiresAt)
	return err
}

func (db *DB) GetMagicLink(ctx context.Context, token string) (*MagicLink, error) {
	var ml MagicLink
	var userID uuid.UUID

	err := db.QueryRow(ctx, `
		SELECT token, user_id, email, used, expires_at, created_at
		FROM magic_links 
		WHERE token = $1
	`, token).Scan(&ml.Token, &userID, &ml.Email, &ml.Used, &ml.ExpiresAt, &ml.CreatedAt)
	if err == pgx.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}

	ml.UserID = userID
	return &ml, nil
}

func (db *DB) MarkMagicLinkUsed(ctx context.Context, token string) error {
	_, err := db.pool.Exec(ctx, `UPDATE magic_links SET used = true WHERE token = $1`, token)
	return err
}

func (db *DB) PutKV(ctx context.Context, key string, value any) error {
	payload, err := json.Marshal(value)
	if err != nil {
		return fmt.Errorf("marshal kv value: %w", err)
	}

	_, err = db.pool.Exec(ctx, `
		INSERT INTO stripe_kv (key, value, created_at, updated_at)
		VALUES ($1, $2, NOW(), NOW())
		ON CONFLICT (key) DO UPDATE
		SET value = EXCLUDED.value, updated_at = NOW()
	`, key, payload)
	return err
}

func (db *DB) GetKV(ctx context.Context, key string, dest any) (bool, error) {
	var payload []byte
	err := db.QueryRow(ctx, `
		SELECT value
		FROM stripe_kv
		WHERE key = $1
	`, key).Scan(&payload)
	if err == pgx.ErrNoRows {
		return false, nil
	}
	if err != nil {
		return false, err
	}
	if err := json.Unmarshal(payload, dest); err != nil {
		return false, fmt.Errorf("unmarshal kv value: %w", err)
	}
	return true, nil
}