package modules

import (
	"net/http"
	"strings"
)

// ModuleMiddleware handles Go module requests directly or passes to next handler
func ModuleMiddleware(moduleHandler http.Handler, next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if isModuleRequest(r) {
			moduleHandler.ServeHTTP(w, r)
			return
		}
		next.ServeHTTP(w, r)
	})
}

// isModuleRequest checks if the request is for Go module endpoints
func isModuleRequest(r *http.Request) bool {
	// Check for go-import meta tag requests
	if r.URL.Query().Get("go-get") == "1" {
		return true
	}

	// Check for Go module proxy endpoints
	return isModuleProxyPath(r.URL.Path)
}

// isModuleProxyPath checks if the path matches Go module proxy endpoints
func isModuleProxyPath(path string) bool {
	// Module proxy endpoints:
	// /{module}/@v/list
	// /{module}/@v/{version}.info
	// /{module}/@v/{version}.mod
	// /{module}/@v/{version}.zip
	// /{module}/@latest

	// Check for @latest endpoint
	if strings.HasSuffix(path, "/@latest") {
		return true
	}

	// Check for @v/ endpoints
	if !strings.Contains(path, "/@v/") {
		return false
	}

	// Valid @v/ endpoint suffixes
	suffixes := []string{"/list", ".info", ".mod", ".zip"}
	for _, suffix := range suffixes {
		if strings.HasSuffix(path, suffix) {
			return true
		}
	}

	return false
}

// ExtractModulePath extracts the module path from a request URL
func ExtractModulePath(path string) string {
	// Remove leading slash
	path = strings.TrimPrefix(path, "/")

	// For proxy endpoints, extract module path before /@v/ or /@latest
	if idx := strings.Index(path, "/@v/"); idx != -1 {
		return path[:idx]
	}

	if strings.HasSuffix(path, "/@latest") {
		return strings.TrimSuffix(path, "/@latest")
	}

	// Remove trailing slash for clean module paths
	return strings.TrimSuffix(path, "/")
}

// ExtractVersion extracts the version from a module proxy request
func ExtractVersion(path string) string {
	if !strings.Contains(path, "/@v/") {
		return ""
	}

	// Extract version from /@v/{version}.{suffix}
	parts := strings.Split(path, "/@v/")
	if len(parts) != 2 {
		return ""
	}

	versionPart := parts[1]

	// Special case for /list endpoint
	if versionPart == "list" {
		return ""
	}

	// Remove suffix (.info, .mod, .zip)
	if idx := strings.LastIndex(versionPart, "."); idx != -1 {
		return versionPart[:idx]
	}

	return versionPart
}