// Package httpapi wires everything together: a JSON API under /api, the
// generated share images, the built frontend's assets, and the HTML shell for
// every other path.
package httpapi

import (
	"net/http"
	"strings"

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

type Server struct {
	cfg   *config.Config
	store *store.Store
	auth  *auth.Service
	shell *shell.Renderer
}

func New(cfg *config.Config, s *store.Store, a *auth.Service, r *shell.Renderer) *Server {
	return &Server{cfg: cfg, store: s, auth: a, shell: r}
}

func (s *Server) Handler() http.Handler {
	if !s.cfg.Dev {
		gin.SetMode(gin.ReleaseMode)
	}
	r := gin.New()
	r.Use(gin.Logger(), gin.Recovery())

	api := r.Group("/api")
	{
		api.GET("/health", s.health)
		api.GET("/campaigns", s.listCampaigns)
		api.GET("/campaigns/:slug", s.getCampaign)
		api.GET("/stats", s.stats)

		api.GET("/auth/session", s.session)
		api.GET("/auth/verify", s.verifyMagicLink)
		api.POST("/auth/magic-link", s.sameOrigin, s.requestMagicLink)
		api.POST("/auth/logout", s.sameOrigin, s.logout)

		admin := api.Group("/admin", s.requireAdmin)
		{
			admin.GET("/campaigns", s.adminListCampaigns)
			admin.GET("/campaigns/:slug", s.adminGetCampaign)
			admin.GET("/owners", s.adminOwners)
			admin.PUT("/campaigns", s.sameOrigin, s.adminSaveCampaign)
			admin.DELETE("/campaigns/:slug", s.sameOrigin, s.adminDeleteCampaign)
		}
	}

	r.GET("/kampanyok/:slug/og.png", s.ogImage)

	// Hashed filenames make these safe to cache forever; index.html is never
	// served from disk, because the shell is what carries the meta tags.
	r.Static("/assets", s.cfg.WebDir+"/assets")
	r.StaticFile("/favicon.ico", s.cfg.WebDir+"/favicon.ico")
	r.StaticFile("/robots.txt", s.cfg.WebDir+"/robots.txt")

	r.NoRoute(s.document)
	return r
}

// sameOrigin is the CSRF guard. The session cookie is SameSite=Lax, which
// already blocks cross-site form posts; this closes the remaining gap for
// requests a page could make with fetch. Same-origin requests from the app
// always carry one of these headers.
func (s *Server) sameOrigin(c *gin.Context) {
	origin := c.GetHeader("Origin")
	if origin == "" {
		if ref := c.GetHeader("Referer"); ref != "" {
			origin = originOf(ref)
		}
	}
	if origin == "" || origin == s.cfg.BaseURL {
		c.Next()
		return
	}
	// In development the Vite dev server is a different port and proxies here.
	if s.cfg.Dev && strings.HasPrefix(origin, "http://localhost:") {
		c.Next()
		return
	}
	c.AbortWithStatusJSON(http.StatusForbidden, gin.H{"error": "cross-origin request refused"})
}

func originOf(rawURL string) string {
	i := strings.Index(rawURL, "://")
	if i < 0 {
		return ""
	}
	rest := rawURL[i+3:]
	if j := strings.IndexByte(rest, '/'); j >= 0 {
		rest = rest[:j]
	}
	return rawURL[:i+3] + rest
}

const userKey = "user"

func (s *Server) requireAdmin(c *gin.Context) {
	user := s.auth.UserFromRequest(c.Request.Context(), c.Request)
	if !s.auth.IsAdmin(user) {
		// 401 rather than 403 even for a signed-in non-admin: the admin surface
		// does not confirm its own existence to accounts that cannot use it.
		c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "unauthorized"})
		return
	}
	c.Set(userKey, user)
	c.Next()
}