package api

import (
	"crypto/rand"
	"database/sql"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"strings"
	"time"

	"git.wntrmute.dev/kyle/mcias/data"
	"github.com/Masterminds/squirrel"
	"github.com/oklog/ulid/v2"
)

type LoginRequest struct {
	Version string     `json:"version"`
	Login   data.Login `json:"login"`
}

type TokenResponse struct {
	Token   string `json:"token"`
	Expires int64  `json:"expires"`
}

type TOTPVerifyRequest struct {
	Version  string `json:"version"`
	Username string `json:"username"`
	TOTPCode string `json:"totp_code"`
}

type ErrorResponse struct {
	Error string `json:"error"`
}

type DatabaseCredentials struct {
	Host     string `json:"host"`
	Port     int    `json:"port"`
	Name     string `json:"name"`
	User     string `json:"user"`
	Password string `json:"password"`
}

func (s *Server) handlePasswordLogin(w http.ResponseWriter, r *http.Request) {
	var req LoginRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		s.sendError(w, "Invalid request format", http.StatusBadRequest)
		return
	}

	if req.Version != "v1" || req.Login.User == "" || req.Login.Password == "" {
		s.sendError(w, "Invalid login request", http.StatusBadRequest)
		return
	}

	user, err := s.getUserByUsername(req.Login.User)
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			s.sendError(w, "Invalid username or password", http.StatusUnauthorized)
		} else {
			s.Logger.Printf("Database error: %v", err)
			s.sendError(w, "Internal server error", http.StatusInternalServerError)
		}
		return
	}

	// Check password only
	if !user.CheckPassword(&req.Login) {
		s.sendError(w, "Invalid username or password", http.StatusUnauthorized)
		return
	}

	// Password is correct, create a token regardless of TOTP status
	token, expires, err := s.createToken(user.ID)
	if err != nil {
		s.Logger.Printf("Token creation error: %v", err)
		// Log the security event
		details := map[string]string{
			"reason": "Token creation error",
			"error":  err.Error(),
		}
		s.LogSecurityEvent(r, "login_attempt", user.ID, user.User, false, details)
		s.sendError(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	// If user has TOTP enabled, include this information in the response
	totpEnabled := user.HasTOTP()

	// Log successful login
	details := map[string]string{
		"token_expires": time.Unix(expires, 0).UTC().Format(time.RFC3339),
		"totp_enabled":  fmt.Sprintf("%t", totpEnabled),
	}
	s.LogSecurityEvent(r, "login_success", user.ID, user.User, true, details)

	// Include TOTP status in the response
	response := struct {
		TokenResponse
		TOTPEnabled bool `json:"totp_enabled"`
	}{
		TokenResponse: TokenResponse{
			Token:   token,
			Expires: expires,
		},
		TOTPEnabled: totpEnabled,
	}

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusOK)
	if err := json.NewEncoder(w).Encode(response); err != nil {
		s.Logger.Printf("Error encoding response: %v", err)
	}
}

func (s *Server) handleTokenLogin(w http.ResponseWriter, r *http.Request) {
	var req LoginRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		s.sendError(w, "Invalid request format", http.StatusBadRequest)
		return
	}

	if req.Version != "v1" || req.Login.User == "" || req.Login.Token == "" {
		s.sendError(w, "Invalid login request", http.StatusBadRequest)
		return
	}

	// Verify the token is valid
	_, err := s.verifyToken(req.Login.User, req.Login.Token)
	if err != nil {
		s.sendError(w, "Invalid or expired token", http.StatusUnauthorized)
		return
	}

	// Renew the existing token instead of creating a new one
	expires, err := s.renewToken(req.Login.User, req.Login.Token)
	if err != nil {
		s.Logger.Printf("Token renewal error: %v", err)
		s.sendError(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusOK)
	if err := json.NewEncoder(w).Encode(TokenResponse{
		Token:   req.Login.Token,
		Expires: expires,
	}); err != nil {
		s.Logger.Printf("Error encoding response: %v", err)
	}
}

func (s *Server) sendError(w http.ResponseWriter, message string, status int) {
	// Log the detailed error message for debugging
	s.Logger.Printf("Error response: %s (Status: %d)", message, status)

	// Create a generic error message based on status code
	publicMessage := "An error occurred processing your request"
	errorCode := fmt.Sprintf("E%000d", status)

	// Customize public messages for common status codes
	// but don't leak specific details about the error
	switch status {
	case http.StatusBadRequest:
		publicMessage = "Invalid request format"
	case http.StatusUnauthorized:
		publicMessage = "Authentication required"
	case http.StatusForbidden:
		publicMessage = "Insufficient permissions"
	case http.StatusNotFound:
		publicMessage = "Resource not found"
	case http.StatusTooManyRequests:
		publicMessage = "Rate limit exceeded"
	case http.StatusInternalServerError:
		publicMessage = "Internal server error"
	}

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)

	response := struct {
		Error     string `json:"error"`
		ErrorCode string `json:"error_code"`
	}{
		Error:     publicMessage,
		ErrorCode: errorCode,
	}

	if err := json.NewEncoder(w).Encode(response); err != nil {
		s.Logger.Printf("Error encoding error response: %v", err)
	}
}

func (s *Server) getUserByUsername(username string) (*data.User, error) {
	// Use squirrel to build the query safely
	query, args, err := squirrel.Select("id", "created", "user", "password", "salt", "totp_secret").
		From("users").
		Where(squirrel.Eq{"user": username}).
		ToSql()
	if err != nil {
		return nil, err
	}

	row := s.DB.QueryRow(query, args...)

	user := &data.User{}
	var totpSecret sql.NullString
	err = row.Scan(&user.ID, &user.Created, &user.User, &user.Password, &user.Salt, &totpSecret)
	if err != nil {
		return nil, err
	}

	// Set TOTP secret if it exists
	if totpSecret.Valid {
		user.TOTPSecret = totpSecret.String
	}

	// Use squirrel to build the roles query safely
	rolesQuery, rolesArgs, err := squirrel.Select("r.role").
		From("roles r").
		Join("user_roles ur ON r.id = ur.rid").
		Where(squirrel.Eq{"ur.uid": user.ID}).
		ToSql()
	if err != nil {
		return nil, err
	}

	rows, err := s.DB.Query(rolesQuery, rolesArgs...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var roles []string
	for rows.Next() {
		var role string
		if err := rows.Scan(&role); err != nil {
			return nil, err
		}
		roles = append(roles, role)
	}
	user.Roles = roles

	return user, nil
}

func (s *Server) createToken(userID string) (string, int64, error) {
	// Generate 16 bytes of random data
	tokenBytes := make([]byte, 16)
	if _, err := rand.Read(tokenBytes); err != nil {
		return "", 0, err
	}

	// Hex encode the random bytes to get a 32-character string.
	token := hex.EncodeToString(tokenBytes)

	expires := time.Now().Add(24 * time.Hour).Unix()
	tokenID := ulid.Make().String()

	// Use squirrel to build the insert query safely
	query, args, err := squirrel.Insert("tokens").
		Columns("id", "uid", "token", "expires").
		Values(tokenID, userID, token, expires).
		ToSql()
	if err != nil {
		return "", 0, err
	}

	_, err = s.DB.Exec(query, args...)
	if err != nil {
		return "", 0, err
	}

	return token, expires, nil
}

func (s *Server) verifyToken(username, token string) (string, error) {
	// Use squirrel to build the query safely
	query, args, err := squirrel.Select("t.uid", "t.expires").
		From("tokens t").
		Join("users u ON t.uid = u.id").
		Where(squirrel.And{
			squirrel.Eq{"u.user": username},
			squirrel.Eq{"t.token": token},
		}).
		ToSql()
	if err != nil {
		return "", err
	}

	var userID string
	var expires int64
	err = s.DB.QueryRow(query, args...).Scan(&userID, &expires)
	if err != nil {
		return "", err
	}

	if expires > 0 && expires < time.Now().Unix() {
		return "", errors.New("token expired")
	}

	return userID, nil
}

func (s *Server) renewToken(username, token string) (int64, error) {
	// First, verify the token exists and get the token ID
	// Use squirrel to build the query safely
	query, args, err := squirrel.Select("t.id").
		From("tokens t").
		Join("users u ON t.uid = u.id").
		Where(squirrel.And{
			squirrel.Eq{"u.user": username},
			squirrel.Eq{"t.token": token},
		}).
		ToSql()
	if err != nil {
		return 0, err
	}

	var tokenID string
	err = s.DB.QueryRow(query, args...).Scan(&tokenID)
	if err != nil {
		return 0, err
	}

	// Update the token's expiry time
	expires := time.Now().Add(24 * time.Hour).Unix()

	// Use squirrel to build the update query safely
	updateQuery, updateArgs, err := squirrel.Update("tokens").
		Set("expires", expires).
		Where(squirrel.Eq{"id": tokenID}).
		ToSql()
	if err != nil {
		return 0, err
	}

	_, err = s.DB.Exec(updateQuery, updateArgs...)
	if err != nil {
		return 0, err
	}

	return expires, nil
}

func (s *Server) handleTOTPVerify(w http.ResponseWriter, r *http.Request) {
	var req TOTPVerifyRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		s.sendError(w, "Invalid request format", http.StatusBadRequest)
		return
	}

	if req.Version != "v1" || req.Username == "" || req.TOTPCode == "" {
		s.sendError(w, "Invalid TOTP verification request", http.StatusBadRequest)
		return
	}

	user, err := s.getUserByUsername(req.Username)
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			s.sendError(w, "User not found", http.StatusUnauthorized)
		} else {
			s.Logger.Printf("Database error: %v", err)
			s.sendError(w, "Internal server error", http.StatusInternalServerError)
		}
		return
	}

	// Check if TOTP is enabled for the user
	if !user.HasTOTP() {
		// Log the security event
		details := map[string]string{
			"reason": "TOTP not enabled for user",
		}
		s.LogSecurityEvent(r, "totp_verification_attempt", user.ID, user.User, false, details)
		s.sendError(w, "TOTP not enabled for user", http.StatusBadRequest)
		return
	}

	// Validate the TOTP code
	valid, validErr := user.ValidateTOTPCode(req.TOTPCode)
	if validErr != nil || !valid {
		// Log the security event
		details := map[string]string{
			"reason": "Invalid TOTP code",
		}
		s.LogSecurityEvent(r, "totp_verification_attempt", user.ID, user.User, false, details)
		s.sendError(w, "Invalid TOTP code", http.StatusUnauthorized)
		return
	}

	// TOTP code is valid, create a token
	token, expires, err := s.createToken(user.ID)
	if err != nil {
		s.Logger.Printf("Token creation error: %v", err)
		// Log the security event
		details := map[string]string{
			"reason": "Token creation error",
			"error":  err.Error(),
		}
		s.LogSecurityEvent(r, "totp_verification_attempt", user.ID, user.User, false, details)
		s.sendError(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	// Log successful TOTP verification
	details := map[string]string{
		"token_expires": time.Unix(expires, 0).UTC().Format(time.RFC3339),
	}
	s.LogSecurityEvent(r, "totp_verification_success", user.ID, user.User, true, details)

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusOK)
	if err := json.NewEncoder(w).Encode(TokenResponse{
		Token:   token,
		Expires: expires,
	}); err != nil {
		s.Logger.Printf("Error encoding response: %v", err)
	}
}

func (s *Server) handleDatabaseCredentials(w http.ResponseWriter, r *http.Request) {
	// Extract authorization header
	authHeader := r.Header.Get("Authorization")
	if authHeader == "" {
		s.sendError(w, "Authorization header required", http.StatusUnauthorized)
		return
	}

	// Check if it's a Bearer token
	parts := strings.Split(authHeader, " ")
	if len(parts) != 2 || strings.ToLower(parts[0]) != "bearer" {
		s.sendError(w, "Invalid authorization format", http.StatusUnauthorized)
		return
	}

	token := parts[1]
	username := r.URL.Query().Get("username")
	if username == "" {
		s.sendError(w, "Username parameter required", http.StatusBadRequest)
		return
	}

	// Verify the token
	userID, err := s.verifyToken(username, token)
	if err != nil {
		s.sendError(w, "Invalid or expired token", http.StatusUnauthorized)
		return
	}

	// Check if user has permission to read database credentials
	user, err := s.getUserByUsername(username)
	if err != nil {
		s.Logger.Printf("Database error: %v", err)
		s.sendError(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	hasPermission, err := user.HasPermission(s.Auth, "database_credentials", "read")
	if err != nil {
		s.Logger.Printf("Permission check error: %v", err)
		s.sendError(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	if !hasPermission {
		s.sendError(w, "Insufficient permissions: requires database_credentials:read permission", http.StatusForbidden)
		return
	}

	// Get database ID from query parameter if provided
	databaseID := r.URL.Query().Get("database_id")

	// Build the query to retrieve databases the user has access to
	queryBuilder := squirrel.Select("d.id", "d.host", "d.port", "d.name", "d.user", "d.password").
		From("database d")

	// If the user is an admin, they can see all databases
	isAdmin := false
	for _, role := range user.Roles {
		if role == "admin" {
			isAdmin = true
			break
		}
	}

	if !isAdmin {
		// Non-admin users can only see databases they're explicitly associated with
		queryBuilder = queryBuilder.Join("database_users du ON d.id = du.db_id").
			Where(squirrel.Eq{"du.uid": userID})
	}

	// If a specific database ID was requested, filter by that
	if databaseID != "" {
		queryBuilder = queryBuilder.Where(squirrel.Eq{"d.id": databaseID})
	}

	query, args, err := queryBuilder.ToSql()
	if err != nil {
		s.Logger.Printf("Query building error: %v", err)
		s.sendError(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	rows, err := s.DB.Query(query, args...)
	if err != nil {
		s.Logger.Printf("Database error: %v", err)
		s.sendError(w, "Internal server error", http.StatusInternalServerError)
		return
	}
	defer rows.Close()

	var databases []DatabaseCredentials
	for rows.Next() {
		var id string
		var creds DatabaseCredentials
		err = rows.Scan(&id, &creds.Host, &creds.Port, &creds.Name, &creds.User, &creds.Password)
		if err != nil {
			s.Logger.Printf("Row scanning error: %v", err)
			s.sendError(w, "Internal server error", http.StatusInternalServerError)
			return
		}
		databases = append(databases, creds)
	}

	if err = rows.Err(); err != nil {
		s.Logger.Printf("Rows iteration error: %v", err)
		s.sendError(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	if len(databases) == 0 {
		s.sendError(w, "No database credentials found", http.StatusNotFound)
		return
	}

	// If a specific database was requested, return just that one
	if databaseID != "" && len(databases) == 1 {
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusOK)
		if err := json.NewEncoder(w).Encode(databases[0]); err != nil {
			s.Logger.Printf("Error encoding response: %v", err)
		}
		return
	}

	// Otherwise return all accessible databases
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusOK)
	if err := json.NewEncoder(w).Encode(databases); err != nil {
		s.Logger.Printf("Error encoding response: %v", err)
	}
}