// Package api wires pansy's HTTP surface: a gin engine with structured logging
// and panic recovery, the versioned JSON API under /api/v1, and (via spa.go) the
// embedded single-page-app fallback. Handlers stay thin — decode, call the
// service layer, encode — so all business logic and permission checks live in
// internal/service (added by later issues).
package api

import (
	"log/slog"
	"net/http"

	"github.com/gin-gonic/gin"
	sloggin "github.com/samber/slog-gin"

	"gitea.stevedudenhoeffer.com/steve/pansy/internal/config"
	"gitea.stevedudenhoeffer.com/steve/pansy/internal/service"
)

// handlers carries the dependencies shared by every HTTP handler. Handlers stay
// thin: decode the request, call a service method, encode the result.
type handlers struct {
	cfg  *config.Config
	svc  *service.Service
	oidc *oidcClient // nil unless OIDC is configured (see config.OIDCReady)
}

// New builds the gin engine with the standard middleware stack and registers the
// API routes against the given service. The embedded SPA fallback is registered
// separately by the caller via RegisterSPA (see spa.go) so the API can be built
// and tested without a web build present.
func New(cfg *config.Config, svc *service.Service) *gin.Engine {
	gin.SetMode(gin.ReleaseMode)

	r := gin.New()
	r.Use(sloggin.New(slog.Default()), gin.Recovery())

	if err := r.SetTrustedProxies(cfg.TrustedProxies); err != nil {
		// Do not leave gin's trust-everyone default active on a parse failure —
		// that would let any client spoof X-Forwarded-For. Fall back to trusting
		// no proxies, which is also the behavior when none are configured.
		slog.Error("api: invalid trusted proxies, trusting none", "error", err)
		_ = r.SetTrustedProxies(nil)
	}

	h := &handlers{cfg: cfg, svc: svc}

	v1 := r.Group("/api/v1")
	// CSRF defense for every state-changing API call (no-op unless PANSY_BASE_URL
	// is set; see csrfGuard).
	v1.Use(h.csrfGuard())
	v1.GET("/healthz", healthz)

	// Auth endpoints are exempt from requireAuth (you can't be logged in yet);
	// /me is the one that needs a session. Feature routers in later issues attach
	// h.requireAuth() to their own protected groups.
	auth := v1.Group("/auth")
	auth.POST("/register", h.register)
	auth.POST("/login", h.login)
	auth.POST("/logout", h.logout)
	auth.GET("/providers", h.providers)
	auth.GET("/me", h.requireAuth(), h.me)

	// OIDC routes exist only when OIDC can actually be offered, so an unconfigured
	// instance 404s them (matching what /auth/providers advertises). Provider
	// discovery is lazy (first request), so a briefly-unreachable IdP doesn't stop
	// the server — or local auth — from starting.
	switch {
	case cfg.OIDCReady():
		h.oidc = newOIDCClient(cfg)
		auth.GET("/oidc/login", h.oidcLogin)
		auth.GET("/oidc/callback", h.oidcCallback)
	case cfg.OIDC.Enabled():
		slog.Warn("api: OIDC is configured but PANSY_BASE_URL is unset; OIDC disabled (an absolute redirect URI is required)")
	}

	// Feature resources sit behind requireAuth, which resolves the session cookie
	// to the actor the service layer's permission checks key off.
	gardens := v1.Group("/gardens", h.requireAuth())
	gardens.GET("", h.listGardens)
	gardens.POST("", h.createGarden)
	gardens.GET("/:id", h.getGarden)
	gardens.PATCH("/:id", h.updateGarden)
	gardens.DELETE("/:id", h.deleteGarden)
	gardens.GET("/:id/full", h.getGardenFull) // one-shot editor load
	gardens.POST("/:id/objects", h.createObject)

	// Objects are addressed by their own id; the service resolves the owning
	// garden for the permission check.
	objects := v1.Group("/objects", h.requireAuth())
	objects.PATCH("/:id", h.updateObject)
	objects.DELETE("/:id", h.deleteObject)

	// Plant catalog: built-ins (seeded, read-only) plus the actor's own rows.
	plants := v1.Group("/plants", h.requireAuth())
	plants.GET("", h.listPlants)
	plants.POST("", h.createPlant)
	plants.PATCH("/:id", h.updatePlant)
	plants.DELETE("/:id", h.deletePlant)

	return r
}

// healthz is a liveness probe: always returns {"ok": true} when the server is up.
func healthz(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{"ok": true})
}