// 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 (
	"context"
	"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)
	// agent holds the live Runner behind an atomic pointer. Unlike oidc it is
	// never nil — the holder is always present and its Runner may be nil when the
	// assistant is off. The chat routes are registered unconditionally and
	// nil-check agent.get(), so a settings change can turn the assistant on or off
	// at runtime (#79) rather than only at boot.
	agent *agentHolder
}

// 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)
	// What this instance can actually do, so the UI offers only what works.
	// Registered after the agent below, because it reports whether the runner
	// actually built — not merely whether it was configured to.
	v1.GET("/capabilities", h.capabilities)

	// 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.POST("/:id/copy", h.copyGarden)         // duplicate a garden the actor owns
	gardens.GET("/:id/full", h.getGardenFull)       // one-shot editor load
	gardens.GET("/:id/history", h.getGardenHistory) // change sets, newest first
	gardens.GET("/:id/years", h.getGardenYears)     // years with planting data
	gardens.POST("/:id/objects", h.createObject)
	// The grow journal hangs off a garden even for entries about one bed or one
	// plop, so it inherits the ordinary garden-role check.
	gardens.GET("/:id/journal", h.listJournal)
	gardens.POST("/:id/journal", h.createJournalEntry)
	gardens.GET("/:id/journal/counts", h.getJournalCounts)

	// Sharing (owner-managed; a recipient may remove their own share).
	gardens.GET("/:id/shares", h.listShares)
	gardens.POST("/:id/shares", h.addShare)
	gardens.PATCH("/:id/shares/:userId", h.updateShare)
	gardens.DELETE("/:id/shares/:userId", h.removeShare)

	// Public read-only share link (owner-managed): GET reports state, POST
	// enables/rotates, DELETE disables. The link itself is served unauthenticated
	// below.
	gardens.GET("/:id/share-link", h.getShareLink)
	gardens.POST("/:id/share-link", h.createShareLink)
	gardens.DELETE("/:id/share-link", h.deleteShareLink)

	// 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)
	objects.POST("/:id/plantings", h.createPlanting) // place a plop in this object
	// Bulk ops. These wrap the same service methods the agent tools call, so an
	// instance with no model configured still gets the most valuable operation in
	// the app — and so "clear bed" is ONE change set rather than one per plop.
	objects.POST("/:id/fill", h.fillObject)
	objects.POST("/:id/clear", h.clearObject)

	// Plantings ("plops") are addressed by their own id; the service resolves the
	// owning object/garden for the permission check.
	plantings := v1.Group("/plantings", h.requireAuth())
	plantings.PATCH("/:id", h.updatePlanting)
	plantings.DELETE("/:id", h.deletePlanting)

	// The garden assistant. Its routes are registered UNCONDITIONALLY and the live
	// Runner sits behind an atomic pointer in the holder, so a settings change can
	// turn the assistant on or off at runtime (#79). Each handler nil-checks
	// agent.get(); a chat request while the assistant is off gets a clean 503
	// (AGENT_DISABLED), not a panic and not a missing route.
	//
	// The holder resolves its initial Runner from settings + environment at
	// construction. If the key never reaches the container, the assistant is off
	// and the reason is logged below — the same operability need #72 added.
	h.agent = newAgentHolder(context.Background(), svc)
	if cfg.Agent.OllamaCloudAPIKey == "" {
		slog.Info("api: garden assistant has no API key",
			"hint", "set OLLAMA_CLOUD_API_KEY in the container's environment (not just the stack's); the model can be chosen in Settings")
	}
	agentGroup := v1.Group("/agent", h.requireAuth())
	agentGroup.POST("/chat", h.agentChat)
	gardens.GET("/:id/agent/history", h.getAgentHistory)
	gardens.DELETE("/:id/agent/history", h.deleteAgentHistory)

	// Instance settings: admin-only, and the first thing to enforce is_admin.
	// requireAdmin runs after requireAuth (it reads the actor requireAuth stored).
	settings := v1.Group("/settings", h.requireAuth(), h.requireAdmin())
	settings.GET("", h.getSettings)
	settings.PATCH("", h.updateSettings)

	// Undo. A change set is addressed by its own id; the service resolves the
	// owning garden for the permission check, same as objects and plantings.
	changeSets := v1.Group("/change-sets", h.requireAuth())
	changeSets.POST("/:id/revert", h.revertChangeSet)

	// Journal entries are addressed by their own id; the service resolves the
	// owning garden for the permission check, same as objects and plantings.
	journal := v1.Group("/journal", h.requireAuth())
	journal.PATCH("/:id", h.updateJournalEntry)
	journal.DELETE("/:id", h.deleteJournalEntry)

	// 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)

	// Seed lots: what the actor bought, and what's left. Private to the buyer,
	// so these hang off the session actor rather than off a garden.
	seedLots := v1.Group("/seed-lots", h.requireAuth())
	seedLots.GET("", h.listSeedLots)
	seedLots.POST("", h.createSeedLot)
	seedLots.GET("/:id", h.getSeedLot)
	seedLots.PATCH("/:id", h.updateSeedLot)
	seedLots.DELETE("/:id", h.deleteSeedLot)
	// Seed-packet capture (#81): scan a photo into a proposal, then create the
	// plant + lot from the confirmed proposal. scan reads only.
	seedLots.POST("/scan", h.scanSeedPacket)
	seedLots.POST("/from-packet", h.createFromPacket)

	// Public, unauthenticated read of a garden by its share token. Deliberately
	// NOT behind requireAuth: the token is the capability, so a logged-out visitor
	// opens a shared link without being redirected to /login or OIDC. Only GET,
	// only the read-only /full payload — never a mutation.
	public := v1.Group("/public")
	public.GET("/gardens/:token", h.getPublicGarden)

	return r
}

// capabilities reports what this instance can actually do, so the UI offers only
// what works.
//
// It reports whether the assistant is live RIGHT NOW, not merely configured:
// the chat routes always exist, but a request while the Runner is nil is refused,
// so offering the tab must track the live Runner. Reading agent.get() (an atomic
// load) means this reflects a settings-driven swap on the very next poll.
func (h *handlers) capabilities(c *gin.Context) {
	// vision advertises whether seed-packet scanning (#81) can be offered — a
	// configured, resolvable vision model + a key. Read per-request so a settings
	// change is reflected on the next poll, same as agent.
	vision := false
	if vis, err := h.svc.EffectiveVision(c.Request.Context()); err == nil {
		vision = vis.Ready()
	}
	c.JSON(http.StatusOK, gin.H{"agent": h.agent.get() != nil, "vision": vision})
}

// 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})
}