package mux

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

type Resource struct {
	mux         *http.ServeMux
	pattern     string
	middlewares []func(http.Handler) http.Handler
	routes      *RouteList
}

// Resource routes mapping by using HTTP verbs
//   - GET  /pattern 				view all resources
//   - GET  /pattern/create		new resource view
//   - POST /pattern 			create a new resource
//   - GET  /pattern/:id			view a resource
//   - PUT  /pattern/:id			update a resource
//   - PATCH  /pattern/:id		partial update a resource
//   - DELETE /resource/:id		delete a resource
func (m *Mux) Resource(pattern string, fn func(res *Resource), mw ...func(http.Handler) http.Handler) {
	if m == nil {
		panic("mux: Resource() called on nil")
	}

	if strings.TrimSpace(pattern) == "" {
		panic("mux: Resource() requires a patter to work")
	}

	if fn == nil {
		panic("mux: Resource() requires callback")
	}

	// Copy root middlewares.
	mws := make([]func(http.Handler) http.Handler, len(m.middlewares)+len(mw))
	copy(mws, m.middlewares)

	// Append inline middlewares.
	if len(mw) > 0 {
		mws = append(mws, mw...)
	}

	fn(&Resource{
		mux:         m.mux,
		pattern:     pattern,
		middlewares: mws,
		routes:      m.routes,
	})
}

// Index of all resource.
//
// GET /pattern
func (res *Resource) Index(h http.HandlerFunc) {
	res.routes.Add(http.MethodGet + " " + res.pattern)
	res.handlerFunc(http.MethodGet, res.pattern, h)
}

// CreateView new resource
//
// GET /pattern/create
func (res *Resource) CreateView(h http.HandlerFunc) {
	p := suffixIt(res.pattern, "create")
	res.routes.Add(http.MethodGet + " " + p)
	res.handlerFunc(http.MethodGet, p, h)
}

// Create a new resource
//
// POST /pattern/create
func (res *Resource) Create(h http.HandlerFunc) {
	res.routes.Add(http.MethodPost + " " + res.pattern)
	res.handlerFunc(http.MethodPost, res.pattern, h)
}

// View a resource
//
// GET /pattern/:id
func (res *Resource) View(h http.HandlerFunc) {
	p := suffixIt(res.pattern, "{id}")
	res.routes.Add(http.MethodGet + " " + p)
	res.handlerFunc(http.MethodGet, p, h)
}

// Update a resource
//
// PUT /pattern/:id
func (res *Resource) Update(h http.HandlerFunc) {
	p := suffixIt(res.pattern, "{id}")
	res.routes.Add(http.MethodPut + " " + p)
	res.handlerFunc(http.MethodPut, p, h)
}

// UpdatePartial resource info
// PATCH /pattern/:id
func (res *Resource) UpdatePartial(h http.HandlerFunc) {
	p := suffixIt(res.pattern, "{id}")
	res.routes.Add(http.MethodPatch + " " + p)
	res.handlerFunc(http.MethodPatch, p, h)
}

// Delete a resource
//
// DELETE /pattern/:id
func (res *Resource) Delete(h http.HandlerFunc) {
	p := suffixIt(res.pattern, "{id}")
	res.routes.Add(http.MethodDelete + " " + p)
	res.handlerFunc(http.MethodDelete, p, h)
}

func (res *Resource) Handle(pattern string, h http.HandlerFunc) {
	p := suffixIt(res.pattern, "{id}")
	res.routes.Add(http.MethodDelete + " " + p)
	res.handlerFunc(http.MethodDelete, p, h)
}

// handlerFunc registers the handler function for the given pattern.
// If the given pattern conflicts, with one that is already registered, HandleFunc
// panics.
func (res *Resource) handlerFunc(method, pattern string, h http.HandlerFunc) {
	if res == nil {
		panic("serve: func handlerFunc() was called on nil")
	}

	if res.mux == nil {
		panic("serve: router mux is nil")
	}

	path := fmt.Sprintf("%s %s", method, pattern)
	res.mux.Handle(path, stack(res.middlewares, h))
}

// Use will register middleware(s) on Router stack.
func (res *Resource) Use(middlewares ...func(http.Handler) http.Handler) {
	if res == nil {
		panic("serve: func Use was called on nil")
	}
	res.middlewares = append(res.middlewares, middlewares...)
}

func suffixIt(str, suffix string) string {
	var p strings.Builder
	p.WriteString(str)
	if !strings.HasSuffix(str, "/") {
		p.WriteString("/")
	}
	p.WriteString(suffix)
	return p.String()
}