package httpx

import (
	"fmt"
	"html/template"
	"io/fs"
	"net/http"
	"net/url"
	"strings"

	"bountyboard/internal/domain"
	"bountyboard/web"
)

// pageData is the payload every template receives.
type pageData struct {
	Title        string
	Active       string // nav highlight key
	User         *domain.User
	DefaultTheme string
	Narrow       bool
	OIDCEnabled  bool
	Error        string
	HasLocalAuth bool
	Scripts      []string
	Data         map[string]any // page-specific extras
}

var templateFuncs = template.FuncMap{
	"initials": func(name string) string {
		parts := strings.Fields(name)
		switch {
		case len(parts) >= 2:
			return strings.ToUpper(string([]rune(parts[0])[:1]) + string([]rune(parts[1])[:1]))
		case len(parts) == 1 && len(parts[0]) > 0:
			return strings.ToUpper(string([]rune(parts[0])[:1]))
		default:
			return "?"
		}
	},
}

// parseTemplates builds one template set per page (layout + page content).
func parseTemplates() (map[string]*template.Template, error) {
	pages, err := fs.Glob(web.FS, "templates/*.html")
	if err != nil {
		return nil, err
	}
	out := make(map[string]*template.Template)
	for _, page := range pages {
		name := strings.TrimPrefix(page, "templates/")
		if name == "layout.html" {
			continue
		}
		t, err := template.New(name).Funcs(templateFuncs).
			ParseFS(web.FS, "templates/layout.html", page)
		if err != nil {
			return nil, fmt.Errorf("parse %s: %w", page, err)
		}
		out[name] = t
	}
	return out, nil
}

func (s *Server) render(w http.ResponseWriter, r *http.Request, page string, data *pageData) {
	t, ok := s.templates[page]
	if !ok {
		s.internalError(w, r, "render", fmt.Errorf("unknown template %q", page))
		return
	}
	if data == nil {
		data = &pageData{}
	}
	if data.DefaultTheme == "" {
		data.DefaultTheme = "light"
		if data.User != nil && data.User.Settings.Theme != "" {
			data.DefaultTheme = data.User.Settings.Theme
		}
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := t.ExecuteTemplate(w, "layout", data); err != nil {
		s.log.Error("execute template", "page", page, "err", err)
	}
}

// pageUser resolves the session for an HTML page; returns nil when not
// logged in (no error response — pages redirect instead).
func (s *Server) pageUser(r *http.Request) *domain.User {
	c, err := r.Cookie(sessionCookie)
	if err != nil || c.Value == "" {
		return nil
	}
	sess, err := s.store.SessionByToken(r.Context(), c.Value)
	if err != nil {
		return nil
	}
	u, err := s.store.UserByID(r.Context(), sess.UserID)
	if err != nil || u.Disabled {
		return nil
	}
	return u
}

// page wraps an HTML handler that requires login: redirects anonymous
// visitors to /login?next=… and forces pending password changes through
// /change-password.
func (s *Server) page(h func(http.ResponseWriter, *http.Request, *domain.User)) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		u := s.pageUser(r)
		if u == nil {
			http.Redirect(w, r, "/login?next="+url.QueryEscape(r.URL.RequestURI()), http.StatusFound)
			return
		}
		if u.MustChangePassword() && r.URL.Path != "/change-password" {
			http.Redirect(w, r, "/change-password", http.StatusFound)
			return
		}
		h(w, r, u)
	}
}

func (s *Server) routesWeb(mux *http.ServeMux) {
	staticFS, err := fs.Sub(web.FS, "static")
	if err != nil {
		panic(err) // embed layout is fixed at compile time
	}
	mux.Handle("GET /static/", http.StripPrefix("/static/",
		cacheControl(http.FileServerFS(staticFS), "public, max-age=3600")))

	mux.HandleFunc("GET /{$}", s.page(func(w http.ResponseWriter, r *http.Request, u *domain.User) {
		s.render(w, r, "home.html", &pageData{Title: "Home", User: u})
	}))

	mux.HandleFunc("GET /login", func(w http.ResponseWriter, r *http.Request) {
		if s.pageUser(r) != nil {
			http.Redirect(w, r, "/", http.StatusFound)
			return
		}
		s.render(w, r, "login.html", &pageData{
			Title: "Log in", Narrow: true,
			OIDCEnabled: s.cfg.OIDC.Enabled(),
			Error:       loginErrorMessage(r.URL.Query().Get("error")),
			Scripts:     []string{"/static/js/login.js"},
		})
	})

	mux.HandleFunc("GET /register", func(w http.ResponseWriter, r *http.Request) {
		if s.pageUser(r) != nil {
			http.Redirect(w, r, "/", http.StatusFound)
			return
		}
		s.render(w, r, "register.html", &pageData{
			Title: "Create account", Narrow: true,
			Scripts: []string{"/static/js/register.js"},
		})
	})

	mux.HandleFunc("GET /change-password", s.page(func(w http.ResponseWriter, r *http.Request, u *domain.User) {
		s.render(w, r, "change-password.html", &pageData{
			Title: "Change password", User: u, Narrow: true,
			Scripts: []string{"/static/js/change-password.js"},
		})
	}))

	mux.HandleFunc("GET /profile", s.page(func(w http.ResponseWriter, r *http.Request, u *domain.User) {
		s.render(w, r, "profile.html", &pageData{
			Title: "Profile", User: u,
			HasLocalAuth: u.Auth.Local != nil,
			Scripts:      []string{"/static/js/profile.js"},
		})
	}))

	mux.HandleFunc("GET /admin", s.page(func(w http.ResponseWriter, r *http.Request, u *domain.User) {
		if !u.Roles.Admin {
			s.render(w, r, "placeholder.html", &pageData{Title: "Not authorized", User: u})
			return
		}
		s.render(w, r, "admin.html", &pageData{
			Title: "Administration", Active: "admin", User: u,
			Scripts: []string{"/static/js/admin.js"},
		})
	}))

	// Placeholders for areas built in later phases; replaced as they land.
	placeholders := map[string]string{
		"/board":              "Bounty Board",
		"/my-tasks":           "My Tasks",
		"/consultant/board":   "Atomization Board",
		"/consultant/reviews": "Review Queue",
		"/consultant/pool":    "Developer Pool",
		"/messages":           "Messages",
		"/metrics":            "Metrics",
	}
	for path, title := range placeholders {
		mux.HandleFunc("GET "+path, s.page(func(w http.ResponseWriter, r *http.Request, u *domain.User) {
			s.render(w, r, "placeholder.html", &pageData{Title: title, User: u})
		}))
	}
}

func loginErrorMessage(code string) string {
	switch code {
	case "":
		return ""
	case "oidc_state_mismatch", "oidc_failed":
		return "SSO sign-in failed. Please try again."
	case "oidc_denied":
		return "SSO sign-in was cancelled."
	case "oidc_email_unverified":
		return "Your SSO email address is not verified; ask your identity provider administrator."
	case "oidc_no_email":
		return "Your SSO identity has no email address; one is required."
	case "account_disabled":
		return "This account is disabled."
	default:
		return "Sign-in failed."
	}
}

func cacheControl(next http.Handler, value string) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Cache-Control", value)
		next.ServeHTTP(w, r)
	})
}