package httpapi

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

	"github.com/gin-gonic/gin"
	"github.com/szabadpalya/api/internal/hu"
	"github.com/szabadpalya/api/internal/shell"
	"github.com/szabadpalya/api/internal/store"
)

const (
	siteTitle = "Szabadpálya — közösségi finanszírozás közéleti projekteknek"
	siteDesc  = "Szabad a pálya. Közösségi finanszírozás magyar közéleti projekteknek, platformdíj nélkül."
)

func pageTitle(s string) string { return s + " · Szabadpálya" }

// bootstrap is what gets inlined into the document so the first route does not
// have to fetch what the server already loaded to build the meta tags.
type bootstrap struct {
	Route string `json:"route"`
	Data  any    `json:"data"`
}

// document renders the HTML shell for any path the API and the asset handlers
// did not claim. React takes over from #root; everything here is <head>.
func (s *Server) document(c *gin.Context) {
	path := strings.TrimSuffix(c.Request.URL.Path, "/")
	if path == "" {
		path = "/"
	}

	// A stray request for a missing asset must not be answered with an HTML
	// page pretending to be a script — that only produces a confusing MIME
	// error in the console instead of an honest 404.
	if strings.HasPrefix(path, "/api/") || strings.HasPrefix(path, "/assets/") {
		c.JSON(http.StatusNotFound, gin.H{"error": "not found"})
		return
	}

	ctx := c.Request.Context()

	switch {
	case path == "/":
		stats, err := s.store.PlatformStats(ctx)
		if err != nil {
			s.failDocument(c, err)
			return
		}
		s.render(c, http.StatusOK, shell.Document{
			Title:       siteTitle,
			Description: siteDesc,
			Canonical:   s.shell.Abs("/"),
			OG:          shell.OpenGraph{URL: s.shell.Abs("/")},
		}, bootstrap{Route: "home", Data: gin.H{"stats": stats}})

	case path == "/kampanyok":
		campaigns, err := s.store.ListCampaigns(ctx)
		if err != nil {
			s.failDocument(c, err)
			return
		}
		s.render(c, http.StatusOK, shell.Document{
			Title:       pageTitle("Projektek"),
			Description: "Böngészd a futó és lezárult közösségi kampányokat a Szabadpályán.",
			Canonical:   s.shell.Abs("/kampanyok"),
			OG:          shell.OpenGraph{URL: s.shell.Abs("/kampanyok")},
		}, bootstrap{Route: "campaigns", Data: gin.H{"campaigns": campaigns}})

	case strings.HasPrefix(path, "/kampanyok/"):
		s.campaignDocument(c, strings.TrimPrefix(path, "/kampanyok/"))

	case path == "/belepes":
		s.render(c, http.StatusOK, shell.Document{
			Title:       pageTitle("Belépés"),
			Description: siteDesc,
		}, bootstrap{Route: "login"})

	case path == "/admin" || strings.HasPrefix(path, "/admin/"):
		// The admin surface is gated by the API, not by this document: the
		// shell is public HTML and carries no data. Keeping it out of search
		// results is the only thing to do here.
		c.Header("X-Robots-Tag", "noindex")
		s.render(c, http.StatusOK, shell.Document{
			Title:       pageTitle("Admin"),
			Description: siteDesc,
		}, bootstrap{Route: "admin"})

	default:
		s.render(c, http.StatusNotFound, shell.Document{
			Title:       pageTitle("Nincs ilyen oldal"),
			Description: siteDesc,
		}, bootstrap{Route: "notfound"})
	}
}

func (s *Server) campaignDocument(c *gin.Context, slug string) {
	campaign, err := s.store.GetCampaignBySlug(c.Request.Context(), slug)
	if errors.Is(err, store.ErrNotFound) {
		s.render(c, http.StatusNotFound, shell.Document{
			Title:       pageTitle("Nincs ilyen kampány"),
			Description: siteDesc,
		}, bootstrap{Route: "notfound"})
		return
	}
	if err != nil {
		s.failDocument(c, err)
		return
	}

	// This description is the share card's subtitle, so it leads with the
	// numbers a reader decides on before it repeats the campaign's own summary.
	pct := hu.ProgressPct(campaign.Raised, campaign.Goal)
	description := fmt.Sprintf("%s gyűlt össze · %d%% · %s támogató. %s",
		hu.FormatHUF(campaign.Raised), pct, hu.FormatNumber(campaign.Backers), campaign.Summary)

	url := s.shell.Abs("/kampanyok/" + campaign.Slug)
	s.render(c, http.StatusOK, shell.Document{
		Title:       pageTitle(campaign.Title),
		Description: description,
		Canonical:   url,
		OG: shell.OpenGraph{
			Title:       campaign.Title,
			Description: description,
			Type:        "article",
			URL:         url,
			Image:       s.shell.Abs("/kampanyok/" + campaign.Slug + "/og.png"),
			ImageAlt:    campaign.Title + " — Szabadpálya kampány",
		},
	}, bootstrap{Route: "campaign", Data: campaign})
}

func (s *Server) render(c *gin.Context, status int, doc shell.Document, data bootstrap) {
	if err := s.shell.Render(c.Writer, status, doc, data); err != nil {
		c.Error(err)
	}
}

// failDocument keeps a database outage from returning a blank page: the shell
// still renders, and the client shows its own error state.
func (s *Server) failDocument(c *gin.Context, err error) {
	c.Error(err)
	s.render(c, http.StatusInternalServerError, shell.Document{
		Title:       pageTitle("Hiba"),
		Description: siteDesc,
	}, bootstrap{Route: "error"})
}