package handler

import (
	"fmt"
	"html/template"
	"io"

	"git.phc.dm.unipi.it/phc/website/appunti"
	"git.phc.dm.unipi.it/phc/website/articles"
	"git.phc.dm.unipi.it/phc/website/auth"
	"git.phc.dm.unipi.it/phc/website/lista_utenti"
	"git.phc.dm.unipi.it/phc/website/model"
	"git.phc.dm.unipi.it/phc/website/rss"
	"git.phc.dm.unipi.it/phc/website/storia"
	"git.phc.dm.unipi.it/phc/website/templates"
	"git.phc.dm.unipi.it/phc/website/util"
)

type Service interface {
	//
	// Pages
	//
	HandleStaticPage(w io.Writer, view string, ctx Context) error

	// Storia
	HandleStoriaPage(w io.Writer, ctx Context) error

	// Appunti
	HandleAppuntiPage(w io.Writer, query string, ctx Context) error
	HandleAppuntiCondivisiPage(w io.Writer, ctx Context) error
	HandleDispensaPage(w io.Writer, id string, ctx Context) error

	// News
	HandleNewsPage(w io.Writer, ctx Context) error

	// Guide
	HandleGuidePage(w io.Writer, ctx Context) error

	// User
	HandleProfilePage(w io.Writer, ctx Context) error

	// Article Pages
	HandleNewsArticlePage(w io.Writer, articleID string, ctx Context) error
	HandleGuideArticlePage(w io.Writer, articleID string, ctx Context) error

	// RSS
	HandleNewsFeedPage(w io.Writer) error
	HandleGuideFeedPage(w io.Writer) error

	//
	// API
	//

	// User
	HandleLogin(username, password string) (*model.Session, error)
	HandleUser(token string) *model.User
	HandleRequiredUser(ctx Context) (*model.User, error)

	// User Listing
	HandleUtenti() ([]*model.User, error)
	HandleListaUtenti() ([]*model.ListUser, error)

	// Appunti
	HandleCreateDispensa(template model.Dispensa, ctx Context) (*model.Dispensa, error)
}

//
// Typed context
//

// UserKey is a typed type for *model.User used to extract a user form a [handler.Context]
const UserKey ContextKey[*model.User] = "user"

func (ctx Context) getUser() *model.User {
	return GetContextValue(ctx, UserKey)
}

// Handler holds references to abstract services for easy testing provided by every module (TODO: Make every field an interface of -Service)
type DefaultHandler struct {
	AuthService           auth.Service
	AppuntiService        appunti.Service
	Renderer              *templates.TemplateRenderer
	NewsArticlesRegistry  *articles.Registry
	GuideArticlesRegistry *articles.Registry
	ListaUtenti           lista_utenti.Service
	Storia                storia.StoriaService
}

var _ Service = &DefaultHandler{}

func (h *DefaultHandler) HandleStaticPage(w io.Writer, view string, ctx Context) error {
	return h.Renderer.Render(w, view, util.Map{
		"User": ctx.getUser(),
	})
}

func (h *DefaultHandler) HandleUtenti() ([]*model.User, error) {
	utenti, err := h.AuthService.GetUsers()
	if err != nil {
		return nil, err
	}

	return utenti, nil
}

func (h *DefaultHandler) HandleListaUtenti() ([]*model.ListUser, error) {
	utenti, err := h.ListaUtenti.GetUtenti()
	if err != nil {
		return nil, err
	}

	return utenti, nil
}

func (h *DefaultHandler) HandleStoriaPage(w io.Writer, ctx Context) error {
	storia, err := h.Storia.GetStoria()
	if err != nil {
		return err
	}

	return h.Renderer.Render(w, "storia.html", util.Map{
		"User":   ctx.getUser(),
		"Storia": storia,
	})
}

func (h *DefaultHandler) HandleAppuntiPage(w io.Writer, query string, ctx Context) error {
	return h.Renderer.Render(w, "appunti.html", util.Map{
		"User":  ctx.getUser(),
		"Query": query,
	})
}

func (h *DefaultHandler) HandleAppuntiCondivisiPage(w io.Writer, ctx Context) error {
	return h.Renderer.Render(w, "appunti-condivisi.html", util.Map{
		"User": ctx.getUser(),
	})
}

func (h *DefaultHandler) HandleDispensaPage(w io.Writer, id string, ctx Context) error {
	dispensa, err := h.AppuntiService.GetDispensa(id)
	if err != nil {
		return err
	}

	return h.Renderer.Render(w, "dispensa.html", util.Map{
		"User":     ctx.getUser(),
		"Dispensa": dispensa,
	})
}

func (h *DefaultHandler) HandleNewsPage(w io.Writer, ctx Context) error {
	articles, err := h.NewsArticlesRegistry.GetArticles()
	if err != nil {
		return err
	}

	return h.Renderer.Render(w, "news.html", util.Map{
		"User":     ctx.getUser(),
		"Articles": articles,
	})
}

func (h *DefaultHandler) HandleGuidePage(w io.Writer, ctx Context) error {
	articles, err := h.GuideArticlesRegistry.GetArticles()
	if err != nil {
		return err
	}

	return h.Renderer.Render(w, "guide.html", util.Map{
		"User":     ctx.getUser(),
		"Articles": articles,
	})
}

func (h *DefaultHandler) HandleLogin(username, password string) (*model.Session, error) {
	session, err := h.AuthService.Login(username, password)
	if err != nil {
		return nil, err
	}

	return session, nil
}

func (h *DefaultHandler) HandleUser(token string) *model.User {
	user, _ := auth.UserForSession(h.AuthService, token)
	return user
}

var ErrNoUser = fmt.Errorf(`user not logged in`)

func (h *DefaultHandler) HandleRequiredUser(ctx Context) (*model.User, error) {
	user := ctx.getUser()
	if user == nil {
		return nil, ErrNoUser
	}

	return user, nil
}

func (h *DefaultHandler) HandleProfilePage(w io.Writer, ctx Context) error {
	user := ctx.getUser()
	if user == nil {
		return ErrNoUser
	}

	return h.Renderer.Render(w, "profilo.html", util.Map{
		"User": user,
	})
}

func (h *DefaultHandler) HandleNewsArticlePage(w io.Writer, articleID string, ctx Context) error {
	article, err := h.NewsArticlesRegistry.GetArticle(articleID)
	if err != nil {
		return err
	}

	html, err := article.Render()
	if err != nil {
		return err
	}

	return h.Renderer.Render(w, "news-base.html", util.Map{
		"User":        ctx.getUser(),
		"Article":     article,
		"ContentHTML": template.HTML(html),
	})
}

func (h *DefaultHandler) HandleGuideArticlePage(w io.Writer, articleID string, ctx Context) error {
	article, err := h.GuideArticlesRegistry.GetArticle(articleID)
	if err != nil {
		return err
	}

	html, err := article.Render()
	if err != nil {
		return err
	}

	return h.Renderer.Render(w, "guide-base.html", util.Map{
		"User":        ctx.getUser(),
		"Article":     article,
		"ContentHTML": template.HTML(html),
	})
}

func (h *DefaultHandler) HandleNewsFeedPage(w io.Writer) error {
	registry, err := h.NewsArticlesRegistry.GetArticles()
	if err != nil {
		return err
	}

	newsFeed := rss.GenerateRssFeed(registry, "news", "Feed Notizie PHC", "https://phc.dm.unipi.it/news", "Le ultime nuove sul PHC.")

	return newsFeed.WriteRss(w)
}

func (h *DefaultHandler) HandleGuideFeedPage(w io.Writer) error {
	registry, err := h.GuideArticlesRegistry.GetArticles()
	if err != nil {
		return err
	}

	guideFeed := rss.GenerateRssFeed(registry, "guide", "Feed Guide PHC", "https://phc.dm.unipi.it/guide", "Le più recenti guide a carattere informatico a cura dei macchinisti del PHC.")

	return guideFeed.WriteRss(w)
}

//
// API
//

func (h *DefaultHandler) HandleCreateDispensa(template model.Dispensa, ctx Context) (*model.Dispensa, error) {
	user := ctx.getUser()
	if user == nil {
		return nil, ErrNoUser
	}

	template.OwnerId = user.Username
	id, err := h.AppuntiService.CreateDispensa(template)
	if err != nil {
		return nil, err
	}

	template.Id = id

	if len(template.Tags) > 0 {
		h.AppuntiService.SetDispensaTags(id, template.Tags)
	}

	return &template, nil
}