package middleware

import (
	"apiserver/common"
	"apiserver/controllers"
	"apiserver/models"
	"apiserver/store"
	logger "apiserver/utils"
	"bytes"
	"encoding/json"
	"errors"
	"io"
	"net/http"
	"strings"

	"github.com/gin-gonic/gin"
	"go.uber.org/zap"
)

func ValidateHandler() gin.HandlerFunc {
	logger.Debug("Enter ValidateHandler() function")
	return func(ctx *gin.Context) {
		if isExcludedPath(ctx.Request.URL.Path) {
			ctx.Next()
			return
		}

		validateHeader()(ctx)
		if ctx.IsAborted() {
			return
		}
		flag := !strings.Contains("multipart/form-data", ctx.Request.Header.Get("Content-Type"))
		if ctx.Request.Method == http.MethodPost && flag == false {
			isValidBody, err := validateRequestBody(ctx)
			if err != nil || !isValidBody {
				controllers.ReturnError(ctx, common.INVALID_PARAMS_CODE,
					common.ERROR_READ_REQUEST_BODY_MSG+": "+err.Error(), nil)
				ctx.Abort()
				return
			}
		}
		if ctx.IsAborted() {
			return
		}
		ctx.Next()
	}
}

// jwtExcludedPaths are the routes that skip JWT validation. An entry is
// matched exactly, unless its last segment is a gin catch-all ("*name", as in
// the route "/swagger/*any"): then any path under the part before the "*"
// matches (bug-1962).
var jwtExcludedPaths = []string{
	"/ping",
	"/xce/v1/auth/logon",
	"/swagger/*any",
	"/xce/v1/auth/logout",
}

func isExcludedPath(path string) bool {
	for _, excludedPath := range jwtExcludedPaths {
		if i := strings.LastIndex(excludedPath, "/*"); i >= 0 {
			if strings.HasPrefix(path, excludedPath[:i+1]) {
				return true
			}
			continue
		}
		if path == excludedPath {
			return true
		}
	}
	return false
}

// Token validation middleware
func validateHeader() gin.HandlerFunc {
	logger.Debug("Enter validateHeader() function")
	return func(ctx *gin.Context) {
		//continue to validate token
		token := ctx.GetHeader("Authorization")
		if token == "" {
			logger.Error("Token is empty")
			controllers.ReturnError(ctx, common.ERROR_AUTH_CHECK_TOKEN_CODE,
				common.ERROR_AUTH_CHECK_TOKEN_EMPTY_MSG, nil)
			ctx.Abort()
			return
		}

		// Validate token (this is a placeholder for your actual token validation logic)
		isValid, err := isValidToken(strings.TrimPrefix(token, "Bearer "), ctx.ClientIP())
		if err != nil {
			logger.Error("Validate token error", zap.Error(err))
			controllers.ReturnError(ctx, common.ERROR_AUTH_CHECK_TOKEN_CODE,
				common.ERROR_AUTH_MSG+": "+err.Error(), nil)
			ctx.Abort()
			return
		}
		if !isValid {
			logger.Error("Token is invalid")
			controllers.ReturnError(ctx, common.ERROR_AUTH_CHECK_TOKEN_CODE,
				common.ERROR_AUTH_MSG, nil)
			ctx.Abort()
			return
		}
	}
}

// isValidToken verifies the token (signature, HS256 only, expiry, not
// revoked by logout) and its IP binding.
func isValidToken(tokenString string, IP string) (bool, error) {
	// Service-account API keys are a distinct credential type from JWTs and
	// carry no IP binding (they're meant for long-lived automated clients
	// like the scheduler-agent MCP server, which may not have a stable IP).
	// API keys also bypass logout-revocation (they outlive JWT sessions).
	if strings.HasPrefix(tokenString, models.APIKeyPrefix) {
		_, ok := store.ValidateAPIKey(tokenString)
		return ok, nil
	}

	// Their hardening (bug-1945/1946/1950): HS256 pinned, default-secret
	// rejected, logout revocation — all centralized in ParseTokenClaims.
	claims, err := controllers.ParseTokenClaims(tokenString)
	if err != nil {
		return false, err
	}
	return claims.IP == IP, nil
}

func validateRequestBody(ctx *gin.Context) (bool, error) {
	logger.Debug("Enter validateRequestBody function")

	// read request body and resolve EOF error
	body, err := ctx.GetRawData()
	if err != nil {
		logger.Error("Failed to read request body", zap.Error(err))
		ctx.Abort()
		return false, err
	}
	if len(body) == 0 {
		logger.Error("Request body is empty")
		ctx.Abort()
		return false, errors.New(common.ERROR_REQUEST_BODY_EMPTY_MSG)
	}

	// reset request body
	ctx.Request.Body = io.NopCloser(bytes.NewBuffer(body))
	// check request body is valid
	if !json.Valid(body) {
		logger.Error("Request body is not valid", zap.Error(err))
		ctx.Abort()
		return false, errors.New(common.ERROR_REQUEST_BODY_NOT_JSON_MSG)
	}
	return true, nil
}