// Package api provides HTTP handlers for the API Gateway
package api

import (
	"net/http"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/golang-jwt/jwt/v5"
	"github.com/google/uuid"
)

// TokenRequest represents an OAuth token request
type TokenRequest struct {
	GrantType    string `json:"grant_type" binding:"required"`
	ClientID     string `json:"client_id" binding:"required"`
	ClientSecret string `json:"client_secret" binding:"required"`
}

// TokenResponse represents an OAuth token response
type TokenResponse struct {
	AccessToken  string `json:"access_token"`
	TokenType    string `json:"token_type"`
	ExpiresIn    int    `json:"expires_in"`
	RefreshToken string `json:"refresh_token,omitempty"`
}

// GetToken handles OAuth token requests
func GetToken(c *gin.Context) {
	var req TokenRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	// Validate credentials (in production, check against database)
	// For now, accept any valid-looking credentials
	if req.GrantType != "client_credentials" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "Unsupported grant type"})
		return
	}

	// Extract tenant ID from client ID (format: sdk_tenantid)
	tenantID := req.ClientID
	if len(tenantID) > 4 {
		tenantID = tenantID[4:] // Remove "sdk_" prefix
	}

	// Generate JWT
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.MapClaims{
		"tenant_id": tenantID,
		"user_id":   req.ClientID,
		"scopes":    []string{"read", "write"},
		"exp":       time.Now().Add(24 * time.Hour).Unix(),
		"iat":       time.Now().Unix(),
	})

	// Sign token (in production, use config.JWTSecret)
	tokenString, _ := token.SignedString([]byte("your-secret-key-change-in-production"))

	c.JSON(http.StatusOK, TokenResponse{
		AccessToken: tokenString,
		TokenType:   "Bearer",
		ExpiresIn:   86400,
	})
}

// RefreshToken handles token refresh requests
func RefreshToken(c *gin.Context) {
	// In production, validate refresh token and issue new access token
	c.JSON(http.StatusOK, gin.H{"message": "Token refreshed"})
}

// =============================================================================
// State Management
// =============================================================================

// GetState retrieves the SDK state for a tenant
func GetState(c *gin.Context) {
	tenantID := c.Param("tenantId")

	// In production, fetch from database
	c.JSON(http.StatusOK, gin.H{
		"tenant_id": tenantID,
		"state": gin.H{
			"version":        1,
			"completedSteps": []string{},
			"currentStep":    "overview",
		},
		"updated_at": time.Now().Format(time.RFC3339),
	})
}

// SaveState saves the SDK state for a tenant
func SaveState(c *gin.Context) {
	var req map[string]interface{}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	// In production, save to database with optimistic locking
	c.JSON(http.StatusOK, gin.H{
		"success":    true,
		"version":    1,
		"updated_at": time.Now().Format(time.RFC3339),
	})
}

// ResetState resets the SDK state for a tenant
func ResetState(c *gin.Context) {
	tenantID, _ := c.Get("tenant_id")

	c.JSON(http.StatusOK, gin.H{
		"success":   true,
		"tenant_id": tenantID,
		"message":   "State reset successfully",
	})
}

// =============================================================================
// DSGVO / Consent
// =============================================================================

// RecordConsent records a consent decision
func RecordConsent(c *gin.Context) {
	var req map[string]interface{}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusCreated, gin.H{
		"id":         uuid.New().String(),
		"created_at": time.Now().Format(time.RFC3339),
		"status":     "ACTIVE",
	})
}

// GetConsents retrieves consents for a user
func GetConsents(c *gin.Context) {
	userID := c.Param("userId")

	c.JSON(http.StatusOK, gin.H{
		"user_id":  userID,
		"consents": []interface{}{},
	})
}

// RevokeConsent revokes a consent
func RevokeConsent(c *gin.Context) {
	consentID := c.Param("consentId")

	c.JSON(http.StatusOK, gin.H{
		"id":         consentID,
		"status":     "REVOKED",
		"revoked_at": time.Now().Format(time.RFC3339),
	})
}

// =============================================================================
// DSGVO / DSR
// =============================================================================

// SubmitDSR submits a new DSR request
func SubmitDSR(c *gin.Context) {
	var req map[string]interface{}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusCreated, gin.H{
		"id":           uuid.New().String(),
		"status":       "PENDING",
		"submitted_at": time.Now().Format(time.RFC3339),
		"deadline":     time.Now().AddDate(0, 1, 0).Format(time.RFC3339),
	})
}

// ListDSRRequests lists DSR requests for a tenant
func ListDSRRequests(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{
		"requests": []interface{}{},
		"total":    0,
	})
}

// UpdateDSRStatus updates the status of a DSR request
func UpdateDSRStatus(c *gin.Context) {
	requestID := c.Param("requestId")

	var req map[string]interface{}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"id":         requestID,
		"status":     req["status"],
		"updated_at": time.Now().Format(time.RFC3339),
	})
}

// =============================================================================
// DSGVO / VVT
// =============================================================================

// GetProcessingActivities retrieves processing activities
func GetProcessingActivities(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{
		"activities": []interface{}{},
		"total":      0,
	})
}

// CreateProcessingActivity creates a new processing activity
func CreateProcessingActivity(c *gin.Context) {
	var req map[string]interface{}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusCreated, gin.H{
		"id":         uuid.New().String(),
		"created_at": time.Now().Format(time.RFC3339),
	})
}

// UpdateProcessingActivity updates a processing activity
func UpdateProcessingActivity(c *gin.Context) {
	activityID := c.Param("activityId")

	c.JSON(http.StatusOK, gin.H{
		"id":         activityID,
		"updated_at": time.Now().Format(time.RFC3339),
	})
}

// DeleteProcessingActivity deletes a processing activity
func DeleteProcessingActivity(c *gin.Context) {
	c.JSON(http.StatusNoContent, nil)
}

// =============================================================================
// DSGVO / TOM
// =============================================================================

// GetTOMs retrieves TOMs
func GetTOMs(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{
		"toms":  []interface{}{},
		"total": 0,
	})
}

// CreateTOM creates a new TOM
func CreateTOM(c *gin.Context) {
	var req map[string]interface{}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusCreated, gin.H{
		"id":         uuid.New().String(),
		"created_at": time.Now().Format(time.RFC3339),
	})
}

// UpdateTOM updates a TOM
func UpdateTOM(c *gin.Context) {
	tomID := c.Param("tomId")

	c.JSON(http.StatusOK, gin.H{
		"id":         tomID,
		"updated_at": time.Now().Format(time.RFC3339),
	})
}

// DeleteTOM deletes a TOM
func DeleteTOM(c *gin.Context) {
	c.JSON(http.StatusNoContent, nil)
}

// =============================================================================
// DSGVO / DSFA
// =============================================================================

// GetDSFAs retrieves DSFAs
func GetDSFAs(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{
		"dsfas": []interface{}{},
		"total": 0,
	})
}

// CreateDSFA creates a new DSFA
func CreateDSFA(c *gin.Context) {
	var req map[string]interface{}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusCreated, gin.H{
		"id":         uuid.New().String(),
		"created_at": time.Now().Format(time.RFC3339),
	})
}

// UpdateDSFA updates a DSFA
func UpdateDSFA(c *gin.Context) {
	dsfaID := c.Param("dsfaId")

	c.JSON(http.StatusOK, gin.H{
		"id":         dsfaID,
		"updated_at": time.Now().Format(time.RFC3339),
	})
}

// =============================================================================
// DSGVO / Retention
// =============================================================================

// GetRetentionPolicies retrieves retention policies
func GetRetentionPolicies(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{
		"policies": []interface{}{},
		"total":    0,
	})
}

// CreateRetentionPolicy creates a new retention policy
func CreateRetentionPolicy(c *gin.Context) {
	var req map[string]interface{}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusCreated, gin.H{
		"id":         uuid.New().String(),
		"created_at": time.Now().Format(time.RFC3339),
	})
}

// UpdateRetentionPolicy updates a retention policy
func UpdateRetentionPolicy(c *gin.Context) {
	policyID := c.Param("policyId")

	c.JSON(http.StatusOK, gin.H{
		"id":         policyID,
		"updated_at": time.Now().Format(time.RFC3339),
	})
}

// DeleteRetentionPolicy deletes a retention policy
func DeleteRetentionPolicy(c *gin.Context) {
	c.JSON(http.StatusNoContent, nil)
}