package controllers

import (
	"net/http"
	"runtime/debug"
	"strings"

	"nearle/services"
	"nearle/utils"

	"github.com/gofiber/fiber/v2"
)

// What is running here, and is it wired up?
//
// ── Why this exists ─────────────────────────────────────────────────────────
//
// On 2026-09-24 the assistant sat switched off in production for most of a day,
// and neither of us could establish WHY from outside the container. Two
// questions had no answer:
//
//  1. which build is deployed?  A redeploy can reuse a cached image, so
//     "I pushed it" and "it is running" are different facts.
//  2. does the server have a model?  `/assistant/status` knows, but it sits
//     behind the session guard, and a 401 from `/v1/web` proves nothing —
//     the middleware answers before routing, so a route that does not exist
//     returns exactly the same 401 as one that does.
//
// Every diagnosis that day was guesswork for want of one request. Hours went
// into probing CORS headers and comparing nginx versions to infer a commit,
// which is what people do when a server will not simply say.
//
// ── What it deliberately does not say ───────────────────────────────────────
//
// Booleans, never values. "The assistant has a model" is operational; WHICH
// model, at which endpoint, under which key is not, and the reason string on
// `/assistant/status` names environment variables — that stays behind the
// guard. Nothing here distinguishes a tenant, so there is nothing to scope.
//
// Unauthenticated on purpose. A health check that needs a credential cannot be
// used by the person trying to work out why credentials are not working, and
// that is precisely when it is wanted.
type HealthController struct {
	assistant services.AssistantService
	// hasDatabase is a construction-time fact, not a live ping. A query per
	// health check is a query per uptime probe, and "configured" is the thing
	// that actually differs between a broken deployment and a working one.
	hasDatabase bool
}

func NewHealthController(assistant services.AssistantService, hasDatabase bool) *HealthController {
	return &HealthController{assistant: assistant, hasDatabase: hasDatabase}
}

// Version is stamped at build time:
//
//	go build -ldflags "-X nearle/controllers.Version=$(git rev-parse --short HEAD)"
//
// Left as "unknown" when nothing stamps it, which is honest — and itself worth
// seeing, because it means the image was not built by the pipeline that does.
var Version = "unknown"

// buildVersion falls back to whatever the toolchain recorded.
//
// `debug.ReadBuildInfo` carries the VCS revision for a build made inside a git
// checkout, so even an image built by hand usually knows its own commit. The
// ldflag is preferred because a Docker build copies the tree without `.git`.
func buildVersion() string {
	if Version != "unknown" && strings.TrimSpace(Version) != "" {
		return Version
	}
	info, ok := debug.ReadBuildInfo()
	if !ok {
		return "unknown"
	}
	for _, setting := range info.Settings {
		if setting.Key == "vcs.revision" && setting.Value != "" {
			if len(setting.Value) > 7 {
				return setting.Value[:7]
			}
			return setting.Value
		}
	}
	return "unknown"
}

func (ctl *HealthController) Health(c *fiber.Ctx) error {
	assistant := false
	if ctl.assistant != nil {
		assistant = ctl.assistant.Available()
	}

	return c.Status(http.StatusOK).JSON(fiber.Map{
		"code": http.StatusOK, "status": true, "message": "Success",
		"details": fiber.Map{
			"version": buildVersion(),
			// Can this server issue console sessions at all?
			//
			// `attachWebSession` logs a minting failure and lets the login
			// succeed without a token, so a server with no signing secret hands
			// out sessions that cannot authenticate: the console renders, and
			// every request after it comes back 401 with no `authorization`
			// header on it. False here is that, stated once, instead of found
			// by reading request headers on a Friday morning.
			"sessions": utils.WebTokenConfigured(),
			// True when a model is configured and the assistant can answer. False
			// is the answer to "I set the key and redeployed, did it take?" —
			// which took a day to establish without it.
			"assistant": assistant,
			"database":  ctl.hasDatabase,
		},
	})
}