package web

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"mime/multipart"
	"net/http"
	"strings"

	h "github.com/theplant/htmlgo"
)

var Default = New()

func Page(pf PageFunc, efs ...interface{}) (p *PageBuilder) {
	p = &PageBuilder{
		b: Default,
	}
	p.pageRenderFunc = pf
	p.RegisterEventFunc("__reload__", reload)
	p.EventFuncs(efs...)
	return
}

type PageBuilder struct {
	EventsHub
	b              *Builder
	pageRenderFunc PageFunc
	maxFormSize    int64
}

func (b *Builder) Page(pf PageFunc) (p *PageBuilder) {
	p = Page(pf).Builder(b)
	return
}

func (p *PageBuilder) Builder(v *Builder) (r *PageBuilder) {
	p.b = v
	r = p
	return
}

func (p *PageBuilder) Wrap(middlewares ...func(in PageFunc) PageFunc) (r *PageBuilder) {
	pf := p.pageRenderFunc
	for _, m := range middlewares {
		pf = m(pf)
	}
	p.pageRenderFunc = pf
	r = p
	return
}

func (p *PageBuilder) MaxFormSize(v int64) (r *PageBuilder) {
	p.maxFormSize = v
	r = p
	return
}

func (p *PageBuilder) EventFuncs(vs ...interface{}) (r *PageBuilder) {
	p.addMultipleEventFuncs(vs...)
	return p
}

func (p *PageBuilder) EventFunc(name string, ef EventFunc) (r *PageBuilder) {
	p.RegisterEventFunc(name, ef)
	return p
}

func (p *PageBuilder) MergeHub(hub *EventsHub) (r *PageBuilder) {
	p.EventsHub.eventFuncs = append(hub.eventFuncs, p.EventsHub.eventFuncs...)
	return p
}

func (p *PageBuilder) render(
	w http.ResponseWriter,
	r *http.Request,
	c context.Context,
	head *PageInjector,
) (pager *PageResponse, body string) {

	if p.pageRenderFunc == nil {
		return
	}

	ctx := MustGetEventContext(c)

	ctx.R = r
	ctx.W = w
	ctx.Injector = head

	pr, err := p.pageRenderFunc(ctx)
	if err != nil {
		panic(err)
	}
	pager = &pr

	if pager.Body == nil {
		panic("page's RenderFunc returns nil body, use pr.Body = root to set it")
	}

	// fmt.Println("eventFuncs count: ", len(p.eventFuncs))
	b, err := pager.Body.MarshalHTML(c)
	if err != nil {
		panic(err)
	}
	body = string(b)

	return
}

func (p *PageBuilder) index(w http.ResponseWriter, r *http.Request) {
	var err error

	var head = &PageInjector{}

	ctx := new(EventContext)
	c := WrapEventContext(r.Context(), ctx)
	pr, body := p.render(w, r, c, head)

	head.setDefault(pr.PageTitle)

	var resp string
	resp, err = p.b.layoutFunc(r, head, body)
	if err != nil {
		panic(err)
	}
	_, err = fmt.Fprintln(w, resp)
	if err != nil {
		panic(err)
	}
}

func (p *PageBuilder) parseForm(r *http.Request) *multipart.Form {
	maxSize := p.maxFormSize
	if maxSize == 0 {
		maxSize = 128 << 20 // 128MB
	}

	err := r.ParseMultipartForm(maxSize)
	if err != nil {
		panic(err)
	}

	return r.MultipartForm
}

const EventFuncIDName = "__execute_event__"

func (p *PageBuilder) executeEvent(w http.ResponseWriter, r *http.Request) {

	ctx := new(EventContext)
	ctx.R = r
	ctx.W = w
	ctx.Injector = &PageInjector{}

	c := WrapEventContext(r.Context(), ctx)

	eventFuncID := r.FormValue(EventFuncIDName)

	// for server side restart and lost all the eventFuncs,
	// but user keep clicking page without refresh page to call p.render to fill up eventFuncs
	// because default added reload
	if len(p.eventFuncs) <= 1 &&
		p.eventFuncById(eventFuncID) == nil &&
		p.b.eventFuncById(eventFuncID) == nil {
		log.Println("Re-render because event funcs gone, might server restarted")
		head := &PageInjector{}
		p.render(w, r, c, head)
	}

	ef := p.eventFuncById(eventFuncID)
	if ef == nil {
		ef = p.b.eventFuncById(eventFuncID)
	}

	if ef == nil {
		log.Printf("event %s not found\n", eventFuncID)
		http.NotFound(w, r)
		return
	}

	er, err := ef(ctx)
	if err != nil {
		panic(err)
	}

	if er.Reload {
		head := &PageInjector{}
		pr, body := p.render(w, r, c, head)
		er.Body = h.RawHTML(body)
		if len(er.PageTitle) == 0 {
			er.PageTitle = pr.PageTitle
		}
	}

	er.Body = h.RawHTML(h.MustString(er.Body, c))

	for _, up := range er.UpdatePortals {
		up.Body = h.RawHTML(h.MustString(up.Body, c))
	}

	err = json.NewEncoder(w).Encode(er)
	if err != nil {
		panic(err)
	}
}

func reload(ctx *EventContext) (r EventResponse, err error) {
	r.Reload = true
	return
}

func (p *PageBuilder) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if strings.Index(r.URL.String(), EventFuncIDName) >= 0 {
		p.executeEvent(w, r)
		return
	}
	p.index(w, r)
}