package handlers

import (
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"strings"
	"time"

	"otpm/api"
	"otpm/middleware"
	"otpm/models"
	"otpm/services"
)

// OTPHandler handles OTP related requests
type OTPHandler struct {
	otpService *services.OTPService
}

// NewOTPHandler creates a new OTPHandler
func NewOTPHandler(otpService *services.OTPService) *OTPHandler {
	return &OTPHandler{
		otpService: otpService,
	}
}

// CreateOTPRequest represents a request to create an OTP
type CreateOTPRequest struct {
	Name      string `json:"name"`
	Issuer    string `json:"issuer"`
	Secret    string `json:"secret"`
	Algorithm string `json:"algorithm"`
	Digits    int    `json:"digits"`
	Period    int    `json:"period"`
}

// CreateOTP handles OTP creation
func (h *OTPHandler) CreateOTP(w http.ResponseWriter, r *http.Request) {
	start := time.Now()

	// Limit request body size
	r.Body = http.MaxBytesReader(w, r.Body, 10*1024) // 10KB max for OTP creation

	// Get user ID from context
	userID, err := middleware.GetUserID(r)
	if err != nil {
		api.NewResponseWriter(w).WriteError(api.ErrUnauthorized)
		log.Printf("CreateOTP unauthorized attempt")
		return
	}

	// Parse request
	var req CreateOTPRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		api.NewResponseWriter(w).WriteErrorWithCode(api.CodeInvalidParams,
			fmt.Sprintf("Invalid request body: %v", err))
		log.Printf("CreateOTP request parse error for user %s: %v", userID, err)
		return
	}

	// Validate OTP parameters
	if req.Secret == "" {
		api.NewResponseWriter(w).WriteErrorWithCode(api.CodeInvalidParams,
			"Secret is required")
		log.Printf("CreateOTP validation failed for user %s: empty secret", userID)
		return
	}

	// Validate algorithm
	supportedAlgos := map[string]bool{
		"SHA1":   true,
		"SHA256": true,
		"SHA512": true,
	}
	if !supportedAlgos[strings.ToUpper(req.Algorithm)] {
		api.NewResponseWriter(w).WriteErrorWithCode(api.CodeInvalidParams,
			"Unsupported algorithm. Supported: SHA1, SHA256, SHA512")
		log.Printf("CreateOTP validation failed for user %s: unsupported algorithm %s",
			userID, req.Algorithm)
		return
	}

	// Create OTP
	otp, err := h.otpService.CreateOTP(r.Context(), userID, models.OTPParams{
		Name:      req.Name,
		Issuer:    req.Issuer,
		Secret:    req.Secret,
		Algorithm: req.Algorithm,
		Digits:    req.Digits,
		Period:    req.Period,
	})

	if err != nil {
		api.NewResponseWriter(w).WriteError(api.ValidationError(err.Error()))
		log.Printf("CreateOTP failed for user %s: %v", userID, err)
		return
	}

	// Log successful creation (mask secret in logs)
	log.Printf("OTP created for user %s (took %v): name=%s issuer=%s algo=%s digits=%d period=%d",
		userID, time.Since(start), req.Name, req.Issuer, req.Algorithm, req.Digits, req.Period)

	api.NewResponseWriter(w).WriteSuccess(otp)
}

// ListOTPs handles listing all OTPs for a user
func (h *OTPHandler) ListOTPs(w http.ResponseWriter, r *http.Request) {
	// Get user ID from context
	userID, err := middleware.GetUserID(r)
	if err != nil {
		api.NewResponseWriter(w).WriteError(api.ErrUnauthorized)
		return
	}

	// Get OTPs
	otps, err := h.otpService.ListOTPs(r.Context(), userID)
	if err != nil {
		api.NewResponseWriter(w).WriteError(api.InternalError(err))
		return
	}

	api.NewResponseWriter(w).WriteSuccess(otps)
}

// GetOTPCode handles generating OTP code
func (h *OTPHandler) GetOTPCode(w http.ResponseWriter, r *http.Request) {
	start := time.Now()

	// Get user ID from context
	userID, err := middleware.GetUserID(r)
	if err != nil {
		api.NewResponseWriter(w).WriteError(api.ErrUnauthorized)
		log.Printf("GetOTPCode unauthorized attempt from IP %s", r.RemoteAddr)
		return
	}

	// Get OTP ID from URL
	otpID := strings.TrimPrefix(r.URL.Path, "/otp/")
	otpID = strings.TrimSuffix(otpID, "/code")

	// Validate OTP ID format
	if len(otpID) != 36 { // Assuming UUID format
		api.NewResponseWriter(w).WriteErrorWithCode(api.CodeInvalidParams,
			"Invalid OTP ID format")
		log.Printf("GetOTPCode invalid OTP ID format: %s (user %s)", otpID, userID)
		return
	}

	// Rate limiting check could be added here
	// (would require redis or similar rate limiter)

	// Generate code
	code, expiresIn, err := h.otpService.GenerateCode(r.Context(), otpID, userID)
	if err != nil {
		api.NewResponseWriter(w).WriteError(api.InternalError(err))
		log.Printf("GetOTPCode failed for user %s OTP %s: %v", userID, otpID, err)
		return
	}

	// Log successful generation (without actual code)
	log.Printf("OTP code generated for user %s OTP %s (took %v, expires in %ds)",
		userID, otpID, time.Since(start), expiresIn)

	api.NewResponseWriter(w).WriteSuccess(map[string]interface{}{
		"code":       code,
		"expires_in": expiresIn,
	})
}

// VerifyOTPRequest represents a request to verify an OTP code
type VerifyOTPRequest struct {
	Code string `json:"code"`
}

// VerifyOTP handles OTP code verification
func (h *OTPHandler) VerifyOTP(w http.ResponseWriter, r *http.Request) {
	// Get user ID from context
	userID, err := middleware.GetUserID(r)
	if err != nil {
		api.NewResponseWriter(w).WriteError(api.ErrUnauthorized)
		return
	}

	// Get OTP ID from URL
	otpID := strings.TrimPrefix(r.URL.Path, "/otp/")
	otpID = strings.TrimSuffix(otpID, "/verify")

	// Parse request
	var req VerifyOTPRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		api.NewResponseWriter(w).WriteErrorWithCode(api.CodeInvalidParams, "Invalid request body")
		return
	}

	// Verify code
	valid, err := h.otpService.VerifyCode(r.Context(), otpID, userID, req.Code)
	if err != nil {
		api.NewResponseWriter(w).WriteError(api.InternalError(err))
		return
	}

	api.NewResponseWriter(w).WriteSuccess(map[string]bool{
		"valid": valid,
	})
}

// UpdateOTPRequest represents a request to update an OTP
type UpdateOTPRequest struct {
	Name      string `json:"name"`
	Issuer    string `json:"issuer"`
	Algorithm string `json:"algorithm"`
	Digits    int    `json:"digits"`
	Period    int    `json:"period"`
}

// UpdateOTP handles OTP update
func (h *OTPHandler) UpdateOTP(w http.ResponseWriter, r *http.Request) {
	// Get user ID from context
	userID, err := middleware.GetUserID(r)
	if err != nil {
		api.NewResponseWriter(w).WriteError(api.ErrUnauthorized)
		return
	}

	// Get OTP ID from URL
	otpID := strings.TrimPrefix(r.URL.Path, "/otp/")

	// Parse request
	var req UpdateOTPRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		api.NewResponseWriter(w).WriteErrorWithCode(api.CodeInvalidParams, "Invalid request body")
		return
	}

	// Update OTP
	otp, err := h.otpService.UpdateOTP(r.Context(), otpID, userID, models.OTPParams{
		Name:      req.Name,
		Issuer:    req.Issuer,
		Algorithm: req.Algorithm,
		Digits:    req.Digits,
		Period:    req.Period,
	})

	if err != nil {
		api.NewResponseWriter(w).WriteError(api.InternalError(err))
		return
	}

	api.NewResponseWriter(w).WriteSuccess(otp)
}

// DeleteOTP handles OTP deletion
func (h *OTPHandler) DeleteOTP(w http.ResponseWriter, r *http.Request) {
	// Get user ID from context
	userID, err := middleware.GetUserID(r)
	if err != nil {
		api.NewResponseWriter(w).WriteError(api.ErrUnauthorized)
		return
	}

	// Get OTP ID from URL
	otpID := strings.TrimPrefix(r.URL.Path, "/otp/")

	// Delete OTP
	if err := h.otpService.DeleteOTP(r.Context(), otpID, userID); err != nil {
		api.NewResponseWriter(w).WriteError(api.InternalError(err))
		return
	}

	api.NewResponseWriter(w).WriteSuccess(map[string]string{
		"message": "OTP deleted successfully",
	})
}

// Routes returns all routes for the OTP handler
func (h *OTPHandler) Routes() map[string]http.HandlerFunc {
	return map[string]http.HandlerFunc{
		"/otp":             h.CreateOTP,
		"/otp/":            h.ListOTPs,
		"/otp/{id}":        h.UpdateOTP,
		"/otp/{id}/code":   h.GetOTPCode,
		"/otp/{id}/verify": h.VerifyOTP,
	}
}