package security

import (
	"fmt"
	"net/http"
	"strconv"
	"strings"
)

// This file provides example implementations of the required security callbacks.
// Copy these functions and modify them to match your authentication and database schema.

// =============================================================================
// EXAMPLE 1: Simple Header-Based Authentication
// =============================================================================

// ExampleAuthenticateFromHeader extracts user ID from X-User-ID header
func ExampleAuthenticateFromHeader(r *http.Request) (userID int, roles string, err error) {
	userIDStr := r.Header.Get("X-User-ID")
	if userIDStr == "" {
		return 0, "", fmt.Errorf("X-User-ID header not provided")
	}

	userID, err = strconv.Atoi(userIDStr)
	if err != nil {
		return 0, "", fmt.Errorf("invalid user ID format: %v", err)
	}

	// Optionally extract roles
	roles = r.Header.Get("X-User-Roles") // comma-separated: "admin,manager"

	return userID, roles, nil
}

// =============================================================================
// EXAMPLE 2: JWT Token Authentication
// =============================================================================

// ExampleAuthenticateFromJWT parses a JWT token and extracts user info
// You'll need to import a JWT library like github.com/golang-jwt/jwt/v5
func ExampleAuthenticateFromJWT(r *http.Request) (userID int, roles string, err error) {
	authHeader := r.Header.Get("Authorization")
	if authHeader == "" {
		return 0, "", fmt.Errorf("authorization header not provided")
	}

	// Extract Bearer token
	tokenString := strings.TrimPrefix(authHeader, "Bearer ")
	if tokenString == authHeader {
		return 0, "", fmt.Errorf("invalid authorization header format")
	}

	// TODO: Parse and validate JWT token
	// Example using github.com/golang-jwt/jwt/v5:
	//
	// token, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
	//     return []byte(os.Getenv("JWT_SECRET")), nil
	// })
	//
	// if err != nil || !token.Valid {
	//     return 0, "", fmt.Errorf("invalid token: %v", err)
	// }
	//
	// claims := token.Claims.(jwt.MapClaims)
	// userID = int(claims["user_id"].(float64))
	// roles = claims["roles"].(string)

	return 0, "", fmt.Errorf("JWT parsing not implemented - see example above")
}

// =============================================================================
// EXAMPLE 3: Session Cookie Authentication
// =============================================================================

// ExampleAuthenticateFromSession validates a session cookie
func ExampleAuthenticateFromSession(r *http.Request) (userID int, roles string, err error) {
	sessionCookie, err := r.Cookie("session_id")
	if err != nil {
		return 0, "", fmt.Errorf("session cookie not found")
	}

	// TODO: Validate session against your session store (Redis, database, etc.)
	// Example:
	//
	// session, err := sessionStore.Get(sessionCookie.Value)
	// if err != nil {
	//     return 0, "", fmt.Errorf("invalid session")
	// }
	//
	// userID = session.UserID
	// roles = session.Roles

	_ = sessionCookie // Suppress unused warning until implemented
	return 0, "", fmt.Errorf("session validation not implemented - see example above")
}

// =============================================================================
// EXAMPLE 4: Column Security - Database Implementation
// =============================================================================

// ExampleLoadColumnSecurityFromDatabase loads column security rules from database
// This implementation assumes the following database schema:
//
//	CREATE TABLE core.secacces (
//	    rid_secacces SERIAL PRIMARY KEY,
//	    rid_hub INTEGER,
//	    control TEXT,              -- Format: "schema.table.column"
//	    accesstype TEXT,           -- "mask" or "hide"
//	    jsonvalue JSONB            -- Masking configuration
//	);
//
//	CREATE TABLE core.hub_link (
//	    rid_hub_parent INTEGER,    -- Security group ID
//	    rid_hub_child INTEGER,     -- User ID
//	    parent_hubtype TEXT        -- 'secgroup'
//	);
func ExampleLoadColumnSecurityFromDatabase(pUserID int, pSchema, pTablename string) ([]ColumnSecurity, error) {
	colSecList := make([]ColumnSecurity, 0)

	// getExtraFilters := func(pStr string) map[string]string {
	// 	mp := make(map[string]string, 0)
	// 	for i, val := range strings.Split(pStr, ",") {
	// 		if i <= 1 {
	// 			continue
	// 		}
	// 		vals := strings.Split(val, ":")
	// 		if len(vals) > 1 {
	// 			mp[vals[0]] = vals[1]
	// 		}
	// 	}
	// 	return mp
	// }

	// rows, err := DBM.DBConn.Raw(fmt.Sprintf(`
	// 	SELECT a.rid_secacces, a.control, a.accesstype, a.jsonvalue
	// 	FROM core.secacces a
	// 	WHERE a.rid_hub IN (
	// 		SELECT l.rid_hub_parent
	// 		FROM core.hub_link l
	// 		WHERE l.parent_hubtype = 'secgroup'
	// 			AND l.rid_hub_child = ?
	// 	)
	// 	AND control ILIKE '%s.%s%%'
	// `, pSchema, pTablename), pUserID).Rows()

	// defer func() {
	// 	if rows != nil {
	// 		rows.Close()
	// 	}
	// }()

	// if err != nil {
	// 	return colSecList, fmt.Errorf("failed to fetch column security from SQL: %v", err)
	// }

	// for rows.Next() {
	// 	var rid int
	// 	var jsondata []byte
	// 	var control, accesstype string

	// 	err = rows.Scan(&rid, &control, &accesstype, &jsondata)
	// 	if err != nil {
	// 		return colSecList, fmt.Errorf("failed to scan column security: %v", err)
	// 	}

	// 	parts := strings.Split(control, ",")
	// 	ids := strings.Split(parts[0], ".")
	// 	if len(ids) < 3 {
	// 		continue
	// 	}

	// 	jsonvalue := make(map[string]interface{})
	// 	if len(jsondata) > 1 {
	// 		err = json.Unmarshal(jsondata, &jsonvalue)
	// 		if err != nil {
	// 			logger.Error("Failed to parse json: %v", err)
	// 		}
	// 	}

	// 	colsec := ColumnSecurity{
	// 		Schema:       pSchema,
	// 		Tablename:    pTablename,
	// 		UserID:       pUserID,
	// 		Path:         ids[2:],
	// 		ExtraFilters: getExtraFilters(control),
	// 		Accesstype:   accesstype,
	// 		Control:      control,
	// 		ID:           int(rid),
	// 	}

	// 	// Parse masking configuration from JSON
	// 	if v, ok := jsonvalue["start"]; ok {
	// 		if value, ok := v.(float64); ok {
	// 			colsec.MaskStart = int(value)
	// 		}
	// 	}

	// 	if v, ok := jsonvalue["end"]; ok {
	// 		if value, ok := v.(float64); ok {
	// 			colsec.MaskEnd = int(value)
	// 		}
	// 	}

	// 	if v, ok := jsonvalue["invert"]; ok {
	// 		if value, ok := v.(bool); ok {
	// 			colsec.MaskInvert = value
	// 		}
	// 	}

	// 	if v, ok := jsonvalue["char"]; ok {
	// 		if value, ok := v.(string); ok {
	// 			colsec.MaskChar = value
	// 		}
	// 	}

	// 	colSecList = append(colSecList, colsec)
	// }

	return colSecList, nil
}

// =============================================================================
// EXAMPLE 5: Column Security - In-Memory/Static Configuration
// =============================================================================

// ExampleLoadColumnSecurityFromConfig loads column security from static config
func ExampleLoadColumnSecurityFromConfig(pUserID int, pSchema, pTablename string) ([]ColumnSecurity, error) {
	// Example: Define security rules in code or load from config file
	securityRules := map[string][]ColumnSecurity{
		"public.employees": {
			{
				Schema:     "public",
				Tablename:  "employees",
				Path:       []string{"ssn"},
				Accesstype: "mask",
				MaskStart:  5,
				MaskEnd:    0,
				MaskChar:   "*",
			},
			{
				Schema:     "public",
				Tablename:  "employees",
				Path:       []string{"salary"},
				Accesstype: "hide",
			},
		},
		"public.customers": {
			{
				Schema:     "public",
				Tablename:  "customers",
				Path:       []string{"credit_card"},
				Accesstype: "mask",
				MaskStart:  12,
				MaskEnd:    0,
				MaskChar:   "*",
			},
		},
	}

	key := fmt.Sprintf("%s.%s", pSchema, pTablename)
	rules, ok := securityRules[key]
	if !ok {
		return []ColumnSecurity{}, nil // No rules for this table
	}

	// Filter by user ID if needed
	// For this example, all rules apply to all users
	return rules, nil
}

// =============================================================================
// EXAMPLE 6: Row Security - Database Implementation
// =============================================================================

// ExampleLoadRowSecurityFromDatabase loads row security rules from database
// This implementation assumes a PostgreSQL function:
//
//	CREATE FUNCTION core.api_sec_rowtemplate(
//	    p_schema TEXT,
//	    p_table TEXT,
//	    p_userid INTEGER
//	) RETURNS TABLE (
//	    p_retval INTEGER,
//	    p_errmsg TEXT,
//	    p_template TEXT,
//	    p_block BOOLEAN
//	);
func ExampleLoadRowSecurityFromDatabase(pUserID int, pSchema, pTablename string) (RowSecurity, error) {
	record := RowSecurity{
		Schema:    pSchema,
		Tablename: pTablename,
		UserID:    pUserID,
	}

	// rows, err := DBM.DBConn.Raw(`
	// 	SELECT r.p_retval, r.p_errmsg, r.p_template, r.p_block
	// 	FROM core.api_sec_rowtemplate(?, ?, ?) r
	// `, pSchema, pTablename, pUserID).Rows()

	// defer func() {
	// 	if rows != nil {
	// 		rows.Close()
	// 	}
	// }()

	// if err != nil {
	// 	return record, fmt.Errorf("failed to fetch row security from SQL: %v", err)
	// }

	// for rows.Next() {
	// 	var retval int
	// 	var errmsg string

	// 	err = rows.Scan(&retval, &errmsg, &record.Template, &record.HasBlock)
	// 	if err != nil {
	// 		return record, fmt.Errorf("failed to scan row security: %v", err)
	// 	}

	// 	if retval != 0 {
	// 		return RowSecurity{}, fmt.Errorf("api_sec_rowtemplate error: %s", errmsg)
	// 	}
	// }

	return record, nil
}

// =============================================================================
// EXAMPLE 7: Row Security - Static Configuration
// =============================================================================

// ExampleLoadRowSecurityFromConfig loads row security from static config
func ExampleLoadRowSecurityFromConfig(pUserID int, pSchema, pTablename string) (RowSecurity, error) {
	// Define row security templates based on entity
	templates := map[string]string{
		"public.orders":    "user_id = {UserID}",                                                                     // Users see only their orders
		"public.documents": "user_id = {UserID} OR is_public = true",                                                 // Users see their docs + public docs
		"public.employees": "department_id IN (SELECT department_id FROM user_departments WHERE user_id = {UserID})", // Complex filter
	}

	// Define blocked entities (no access at all)
	blockedEntities := map[string][]int{
		"public.admin_logs": {},        // All users blocked (empty list = block all)
		"public.audit_logs": {1, 2, 3}, // Block users 1, 2, 3
	}

	key := fmt.Sprintf("%s.%s", pSchema, pTablename)

	// Check if entity is blocked for this user
	if blockedUsers, ok := blockedEntities[key]; ok {
		if len(blockedUsers) == 0 {
			// Block all users
			return RowSecurity{
				Schema:    pSchema,
				Tablename: pTablename,
				UserID:    pUserID,
				HasBlock:  true,
			}, nil
		}
		// Check if specific user is blocked
		for _, blockedUserID := range blockedUsers {
			if blockedUserID == pUserID {
				return RowSecurity{
					Schema:    pSchema,
					Tablename: pTablename,
					UserID:    pUserID,
					HasBlock:  true,
				}, nil
			}
		}
	}

	// Get template for this entity
	template, ok := templates[key]
	if !ok {
		// No row security defined - allow all rows
		return RowSecurity{
			Schema:    pSchema,
			Tablename: pTablename,
			UserID:    pUserID,
			Template:  "",
			HasBlock:  false,
		}, nil
	}

	return RowSecurity{
		Schema:    pSchema,
		Tablename: pTablename,
		UserID:    pUserID,
		Template:  template,
		HasBlock:  false,
	}, nil
}

// =============================================================================
// SETUP HELPER: Configure All Callbacks
// =============================================================================

// SetupCallbacksExample shows how to configure all callbacks
func SetupCallbacksExample() {
	// Option 1: Use database-backed security (production)
	GlobalSecurity.AuthenticateCallback = ExampleAuthenticateFromJWT
	GlobalSecurity.LoadColumnSecurityCallback = ExampleLoadColumnSecurityFromDatabase
	GlobalSecurity.LoadRowSecurityCallback = ExampleLoadRowSecurityFromDatabase

	// Option 2: Use static configuration (development/testing)
	// GlobalSecurity.AuthenticateCallback = ExampleAuthenticateFromHeader
	// GlobalSecurity.LoadColumnSecurityCallback = ExampleLoadColumnSecurityFromConfig
	// GlobalSecurity.LoadRowSecurityCallback = ExampleLoadRowSecurityFromConfig

	// Option 3: Mix and match
	// GlobalSecurity.AuthenticateCallback = ExampleAuthenticateFromJWT
	// GlobalSecurity.LoadColumnSecurityCallback = ExampleLoadColumnSecurityFromConfig
	// GlobalSecurity.LoadRowSecurityCallback = ExampleLoadRowSecurityFromDatabase
}