package storage

import (
	"context"
	"errors"
	"net/netip"
	"time"

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

	"github.com/alchemistkay/guestguard/internal/domain"
)

// EmailVerificationRepo manages single-use email verification tokens.
type EmailVerificationRepo struct {
	pool *pgxpool.Pool
}

func NewEmailVerificationRepo(db *DB) *EmailVerificationRepo {
	return &EmailVerificationRepo{pool: db.Pool}
}

func (r *EmailVerificationRepo) Create(ctx context.Context, userID uuid.UUID, hash string, expiresAt time.Time) error {
	_, err := r.pool.Exec(ctx, `
        INSERT INTO email_verification_tokens (token_hash, user_id, expires_at)
        VALUES ($1, $2, $3)
    `, hash, userID, expiresAt)
	return err
}

// Consume atomically marks the token as used and returns the owning user_id.
// Returns ErrAuthTokenNotFound / ErrAuthTokenConsumed / ErrAuthTokenExpired.
func (r *EmailVerificationRepo) Consume(ctx context.Context, hash string) (uuid.UUID, error) {
	const q = `
        UPDATE email_verification_tokens
        SET consumed_at = now()
        WHERE token_hash = $1
          AND consumed_at IS NULL
          AND expires_at > now()
        RETURNING user_id
    `
	var uid uuid.UUID
	if err := r.pool.QueryRow(ctx, q, hash).Scan(&uid); err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return uuid.Nil, classifyAuthTokenLookup(ctx, r.pool,
				"SELECT consumed_at, expires_at FROM email_verification_tokens WHERE token_hash=$1",
				hash)
		}
		return uuid.Nil, err
	}
	return uid, nil
}

// PasswordResetRepo manages single-use password-reset tokens.
type PasswordResetRepo struct {
	pool *pgxpool.Pool
}

func NewPasswordResetRepo(db *DB) *PasswordResetRepo {
	return &PasswordResetRepo{pool: db.Pool}
}

func (r *PasswordResetRepo) Create(ctx context.Context, userID uuid.UUID, hash string, expiresAt time.Time) error {
	_, err := r.pool.Exec(ctx, `
        INSERT INTO password_reset_tokens (token_hash, user_id, expires_at)
        VALUES ($1, $2, $3)
    `, hash, userID, expiresAt)
	return err
}

func (r *PasswordResetRepo) Consume(ctx context.Context, hash string) (uuid.UUID, error) {
	const q = `
        UPDATE password_reset_tokens
        SET consumed_at = now()
        WHERE token_hash = $1
          AND consumed_at IS NULL
          AND expires_at > now()
        RETURNING user_id
    `
	var uid uuid.UUID
	if err := r.pool.QueryRow(ctx, q, hash).Scan(&uid); err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return uuid.Nil, classifyAuthTokenLookup(ctx, r.pool,
				"SELECT consumed_at, expires_at FROM password_reset_tokens WHERE token_hash=$1",
				hash)
		}
		return uuid.Nil, err
	}
	return uid, nil
}

// RefreshTokenRepo manages refresh-token rows. Refresh tokens are rotated:
// every refresh issues a new token and revokes the old one, recording the
// chain in `replaced_by` so we can detect replay (a revoked token being
// presented again triggers a family-wide revocation).
type RefreshTokenRepo struct {
	pool *pgxpool.Pool
}

func NewRefreshTokenRepo(db *DB) *RefreshTokenRepo {
	return &RefreshTokenRepo{pool: db.Pool}
}

type RefreshToken struct {
	Hash       string
	UserID     uuid.UUID
	ExpiresAt  time.Time
	RevokedAt  *time.Time
	ReplacedBy *string
	UserAgent  string
	IPAddress  *netip.Addr
	CreatedAt  time.Time
}

type CreateRefreshTokenParams struct {
	Hash      string
	UserID    uuid.UUID
	ExpiresAt time.Time
	UserAgent string
	IPAddress string
}

func (r *RefreshTokenRepo) Create(ctx context.Context, p CreateRefreshTokenParams) error {
	ip := parseIP(p.IPAddress)
	_, err := r.pool.Exec(ctx, `
        INSERT INTO refresh_tokens (token_hash, user_id, expires_at, user_agent, ip_address)
        VALUES ($1, $2, $3, NULLIF($4, ''), $5)
    `, p.Hash, p.UserID, p.ExpiresAt, p.UserAgent, ip)
	return err
}

func (r *RefreshTokenRepo) Get(ctx context.Context, hash string) (*RefreshToken, error) {
	const q = `
        SELECT token_hash, user_id, expires_at, revoked_at, replaced_by,
               COALESCE(user_agent, ''), host(ip_address), created_at
        FROM refresh_tokens WHERE token_hash = $1
    `
	var rt RefreshToken
	var ipText *string
	if err := r.pool.QueryRow(ctx, q, hash).Scan(
		&rt.Hash, &rt.UserID, &rt.ExpiresAt, &rt.RevokedAt, &rt.ReplacedBy,
		&rt.UserAgent, &ipText, &rt.CreatedAt,
	); err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, domain.ErrAuthTokenNotFound
		}
		return nil, err
	}
	if ipText != nil && *ipText != "" {
		if addr, err := netip.ParseAddr(*ipText); err == nil {
			rt.IPAddress = &addr
		}
	}
	return &rt, nil
}

// Rotate atomically (in a transaction) marks the old token revoked and
// inserts the new one with replaced_by set. Returns ErrAuthTokenNotFound or
// ErrRefreshTokenRevoked if the old token is missing or already revoked.
func (r *RefreshTokenRepo) Rotate(ctx context.Context, oldHash string, next CreateRefreshTokenParams) error {
	tx, err := r.pool.Begin(ctx)
	if err != nil {
		return err
	}
	defer tx.Rollback(ctx)

	var revokedAt *time.Time
	var userID uuid.UUID
	var expiresAt time.Time
	err = tx.QueryRow(ctx, `
        SELECT user_id, expires_at, revoked_at
        FROM refresh_tokens WHERE token_hash = $1 FOR UPDATE
    `, oldHash).Scan(&userID, &expiresAt, &revokedAt)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return domain.ErrAuthTokenNotFound
		}
		return err
	}
	if revokedAt != nil {
		// Replay of a revoked refresh token — revoke the entire family.
		if _, err := tx.Exec(ctx, `
            UPDATE refresh_tokens SET revoked_at = now()
            WHERE user_id = $1 AND revoked_at IS NULL
        `, userID); err != nil {
			return err
		}
		if err := tx.Commit(ctx); err != nil {
			return err
		}
		return domain.ErrRefreshTokenRevoked
	}
	if time.Now().After(expiresAt) {
		return domain.ErrAuthTokenExpired
	}
	if next.UserID != userID {
		return errors.New("refresh token user mismatch")
	}

	ip := parseIP(next.IPAddress)
	if _, err := tx.Exec(ctx, `
        INSERT INTO refresh_tokens (token_hash, user_id, expires_at, user_agent, ip_address)
        VALUES ($1, $2, $3, NULLIF($4, ''), $5)
    `, next.Hash, next.UserID, next.ExpiresAt, next.UserAgent, ip); err != nil {
		return err
	}
	if _, err := tx.Exec(ctx, `
        UPDATE refresh_tokens SET revoked_at = now(), replaced_by = $2
        WHERE token_hash = $1
    `, oldHash, next.Hash); err != nil {
		return err
	}
	return tx.Commit(ctx)
}

func (r *RefreshTokenRepo) Revoke(ctx context.Context, hash string) error {
	tag, err := r.pool.Exec(ctx, `
        UPDATE refresh_tokens SET revoked_at = now()
        WHERE token_hash = $1 AND revoked_at IS NULL
    `, hash)
	if err != nil {
		return err
	}
	if tag.RowsAffected() == 0 {
		return domain.ErrAuthTokenNotFound
	}
	return nil
}

func (r *RefreshTokenRepo) RevokeAllForUser(ctx context.Context, userID uuid.UUID) error {
	_, err := r.pool.Exec(ctx, `
        UPDATE refresh_tokens SET revoked_at = now()
        WHERE user_id = $1 AND revoked_at IS NULL
    `, userID)
	return err
}

func parseIP(s string) any {
	if s == "" {
		return nil
	}
	addr, err := netip.ParseAddr(s)
	if err != nil {
		return nil
	}
	return addr.String()
}

func classifyAuthTokenLookup(ctx context.Context, pool *pgxpool.Pool, q, hash string) error {
	var consumedAt *time.Time
	var expiresAt time.Time
	if err := pool.QueryRow(ctx, q, hash).Scan(&consumedAt, &expiresAt); err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return domain.ErrAuthTokenNotFound
		}
		return err
	}
	if consumedAt != nil {
		return domain.ErrAuthTokenConsumed
	}
	if time.Now().After(expiresAt) {
		return domain.ErrAuthTokenExpired
	}
	return domain.ErrAuthTokenNotFound
}