// Copyright 2017-2025 WIT.COM Inc. All rights reserved.
// Use of this source code is governed by the GPL 3.0

package ginpb

// this is similar to 'gin' but specifically only for
// sending and working with protocol buffers
//
// also, it is as close to possible a golang 'primitive'
// package (there is no go.sum file)

import (
	"log"
	"net/http"
	"net/url"
	"regexp"
	"sync"
	"text/template"
)

// Param is a single URL parameter, consisting of a key and a value.
type Param struct {
	Key   string
	Value string
}

// Params is a Param-slice, as returned by the router.
// The slice is ordered, the first URL parameter is also the first slice value.
// It is therefore safe to read values by the index.
type Params []Param

func (engine *Engine) allocateContext(maxParams uint16) *Context {
	v := make(Params, 0, maxParams)
	return &Context{engine: engine, Params: &v}
}

func New(opts ...OptionFunc) *Engine {
	engine := &Engine{
		RouterGroup: RouterGroup{
			Handlers: nil,
			basePath: "/",
			root:     true,
		},
		FuncMap:         template.FuncMap{},
		RemoteIPHeaders: []string{"X-Forwarded-For", "X-Real-IP"},
		trustedProxies:  []string{"0.0.0.0/0", "::/0"},
	}
	engine.RouterGroup.engine = engine
	engine.pool.New = func() any {
		return engine.allocateContext(engine.maxParams)
	}
	return engine.With(opts...)
}

// With returns a Engine with the configuration set in the OptionFunc.
func (engine *Engine) With(opts ...OptionFunc) *Engine {
	for _, opt := range opts {
		opt(engine)
	}

	return engine
}

func Default(opts ...OptionFunc) *Engine {
	engine := New()
	// engine.Use(Logger(), Recovery())
	return engine.With(opts...)
}

// Context is the most important part of gin. It allows us to pass variables between middleware,
// manage the flow, validate the JSON of a request and render a JSON response for example.
type Context struct {
	writermem responseWriter
	engine    *Engine
	Params    *Params
	Request   *http.Request
	handlers  HandlersChain

	// queryCache caches the query result from c.Request.URL.Query().
	queryCache url.Values

	// formCache caches c.Request.PostForm, which contains the parsed form data from POST, PATCH,
	// or PUT body parameters.
	formCache url.Values

	// SameSite allows a server to define a cookie attribute making it impossible for
	// the browser to send this cookie along with cross-site requests.
	sameSite http.SameSite
}

// HandlerFunc defines the handler used by gin middleware as return value.
type HandlerFunc func(*Context)

// OptionFunc defines the function to change the default configuration
type OptionFunc func(*Engine)

// HandlersChain defines a HandlerFunc slice.
type HandlersChain []HandlerFunc

// Last returns the last handler in the chain. i.e. the last handler is the main one.
func (c HandlersChain) Last() HandlerFunc {
	if length := len(c); length > 0 {
		return c[length-1]
	}
	return nil
}

// RouterGroup is used internally to configure router, a RouterGroup is associated with
// a prefix and an array of handlers (middleware).
type RouterGroup struct {
	Handlers HandlersChain
	basePath string
	engine   *Engine
	root     bool
}

// Engine is the framework's instance, it contains the muxer, middleware and configuration settings.
// Create an instance of Engine, by using New() or Default()
type Engine struct {
	RouterGroup

	// RedirectTrailingSlash enables automatic redirection if the current route can't be matched but a
	// handler for the path with (without) the trailing slash exists.
	// For example if /foo/ is requested but a route only exists for /foo, the
	// client is redirected to /foo with http status code 301 for GET requests
	// and 307 for all other request methods.
	RedirectTrailingSlash bool

	// RedirectFixedPath if enabled, the router tries to fix the current request path, if no
	// handle is registered for it.
	// First superfluous path elements like ../ or // are removed.
	// Afterwards the router does a case-insensitive lookup of the cleaned path.
	// If a handle can be found for this route, the router makes a redirection
	// to the corrected path with status code 301 for GET requests and 307 for
	// all other request methods.
	// For example /FOO and /..//Foo could be redirected to /foo.
	// RedirectTrailingSlash is independent of this option.
	RedirectFixedPath bool

	// HandleMethodNotAllowed if enabled, the router checks if another method is allowed for the
	// current route, if the current request can not be routed.
	// If this is the case, the request is answered with 'Method Not Allowed'
	// and HTTP status code 405.
	// If no other Method is allowed, the request is delegated to the NotFound
	// handler.
	HandleMethodNotAllowed bool

	// ForwardedByClientIP if enabled, client IP will be parsed from the request's headers that
	// match those stored at `(*gin.Engine).RemoteIPHeaders`. If no IP was
	// fetched, it falls back to the IP obtained from
	// `(*gin.Context).Request.RemoteAddr`.
	ForwardedByClientIP bool

	// AppEngine was deprecated.
	// Deprecated: USE `TrustedPlatform` WITH VALUE `gin.PlatformGoogleAppEngine` INSTEAD
	// #726 #755 If enabled, it will trust some headers starting with
	// 'X-AppEngine...' for better integration with that PaaS.
	AppEngine bool

	// UseRawPath if enabled, the url.RawPath will be used to find parameters.
	UseRawPath bool

	// UnescapePathValues if true, the path value will be unescaped.
	// If UseRawPath is false (by default), the UnescapePathValues effectively is true,
	// as url.Path gonna be used, which is already unescaped.
	UnescapePathValues bool

	// RemoveExtraSlash a parameter can be parsed from the URL even with extra slashes.
	// See the PR #1817 and issue #1644
	RemoveExtraSlash bool

	// RemoteIPHeaders list of headers used to obtain the client IP when
	// `(*gin.Engine).ForwardedByClientIP` is `true` and
	// `(*gin.Context).Request.RemoteAddr` is matched by at least one of the
	// network origins of list defined by `(*gin.Engine).SetTrustedProxies()`.
	RemoteIPHeaders []string

	// TrustedPlatform if set to a constant of value gin.Platform*, trusts the headers set by
	// that platform, for example to determine the client IP
	TrustedPlatform string

	// MaxMultipartMemory value of 'maxMemory' param that is given to http.Request's ParseMultipartForm
	// method call.
	MaxMultipartMemory int64

	// UseH2C enable h2c support.
	UseH2C bool

	// ContextWithFallback enable fallback Context.Deadline(), Context.Done(), Context.Err() and Context.Value() when Context.Request.Context() is not nil.
	ContextWithFallback bool

	FuncMap        template.FuncMap
	trustedProxies []string
	pool           sync.Pool
	maxParams      uint16
	/*
		delims           render.Delims
		secureJSONPrefix string
		HTMLRender       render.HTMLRender
		allNoRoute       HandlersChain
		allNoMethod      HandlersChain
		noRoute          HandlersChain
		noMethod         HandlersChain
		trees            methodTrees
		maxSections      uint16
		trustedCIDRs     []*net.IPNet
	*/
}

// GET is a shortcut for router.Handle("GET", path, handlers).
func (group *RouterGroup) GET(relativePath string, handlers ...HandlerFunc) IRoutes {
	return group.handle(http.MethodGet, relativePath, handlers)
}

// IRouter defines all router handle interface includes single and group router.
type IRouter interface {
	IRoutes
	Group(string, ...HandlerFunc) *RouterGroup
	Any(string, ...HandlerFunc) IRoutes
}

// IRoutes defines all router handle interface.
type IRoutes interface {
	// Use(...HandlerFunc) IRoutes

	// Handle(string, string, ...HandlerFunc) IRoutes
	Any(string, ...HandlerFunc) IRoutes
	GET(string, ...HandlerFunc) IRoutes
	// POST(string, ...HandlerFunc) IRoutes
	// DELETE(string, ...HandlerFunc) IRoutes
}

func (group *RouterGroup) handle(httpMethod, relativePath string, handlers HandlersChain) IRoutes {
	// absolutePath := group.calculateAbsolutePath(relativePath)
	handlers = group.combineHandlers(handlers)
	group.engine.addRoute(httpMethod, relativePath, handlers)
	return group.returnObj()
}

func (group *RouterGroup) combineHandlers(handlers HandlersChain) HandlersChain {
	finalSize := len(group.Handlers) + len(handlers)
	// assert1(finalSize < int(abortIndex), "too many handlers")
	mergedHandlers := make(HandlersChain, finalSize)
	copy(mergedHandlers, group.Handlers)
	copy(mergedHandlers[len(group.Handlers):], handlers)
	return mergedHandlers
}

func (engine *Engine) addRoute(method, path string, handlers HandlersChain) {
	// assert1(path[0] == '/', "path must begin with '/'")
}

func (group *RouterGroup) returnObj() IRoutes {
	if group.root {
		return group.engine
	}
	return group
}

// Any registers a route that matches all the HTTP methods.
// GET, POST, PUT, PATCH, HEAD, OPTIONS, DELETE, CONNECT, TRACE.
func (group *RouterGroup) Any(relativePath string, handlers ...HandlerFunc) IRoutes {
	for _, method := range anyMethods {
		group.handle(method, relativePath, handlers)
	}

	return group.returnObj()
}

var (
	// regEnLetter matches english letters for http method name
	regEnLetter = regexp.MustCompile("^[A-Z]+$")

	// anyMethods for RouterGroup Any method
	anyMethods = []string{
		http.MethodGet, http.MethodPost, http.MethodPut, http.MethodPatch,
		http.MethodHead, http.MethodOptions, http.MethodDelete, http.MethodConnect,
		http.MethodTrace,
	}
)

// Run attaches the router to a http.Server and starts listening and serving HTTP requests.
// It is a shortcut for http.ListenAndServe(addr, router)
// Note: this method will block the calling goroutine indefinitely unless an error happens.
func (engine *Engine) Run(addr string) (err error) {
	// defer func() { debugPrintError(err) }()

	/*
		if engine.isUnsafeTrustedProxies() {
			debugPrint("[WARNING] You trusted all proxies, this is NOT safe. We recommend you to set a value.\n" +
				"Please check https://github.com/gin-gonic/gin/blob/master/docs/doc.md#dont-trust-all-proxies for details.")
		}
	*/
	// engine.updateRouteTrees()
	// address := resolveAddress(addr)
	address := addr
	log.Printf("Listening and serving HTTP on %s\n", address)
	err = http.ListenAndServe(address, engine.Handler())
	return
}

func (engine *Engine) Handler() http.Handler {
	return engine
}

// ServeHTTP conforms to the http.Handler interface.
func (engine *Engine) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	c := engine.pool.Get().(*Context)
	c.writermem.reset(w)
	c.Request = req
	// c.reset()

	// engine.handleHTTPRequest(c)

	engine.pool.Put(c)
}