package controllers

import (
	"errors"
	"net/http"
	"strings"

	"nearle/middleware"
	"nearle/services"
	"nearle/services/tools"
	"nearle/utils"

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

// Nearle Buddy's HTTP surface.
//
//	POST /v1/web/assistant/ask      a question → an answer, and what it ran
//	POST /v1/web/assistant/approve  a card the person pressed → the change, made
//	GET  /v1/web/assistant/status   is this switched on here?
//
// ── Where the caller comes from ─────────────────────────────────────────────
//
// `middleware.WebAuth` parks the verified claims on the request, and this
// builds the tool caller from those and from nothing else. There is no tenant
// field on the request body — deliberately, so there is nothing for a model or
// a caller to fill in. The console asks "what is stuck?" and the server already
// knows whose shop that means.
type AssistantController struct {
	assistant services.AssistantService
}

func NewAssistantController(assistant services.AssistantService) *AssistantController {
	return &AssistantController{assistant: assistant}
}

type assistantApproveRequest struct {
	Agent string `json:"agent"`
	// The card exactly as it was handed out. Opaque to the console — it is
	// signed, and anything the browser changed stops it verifying.
	Card string `json:"card"`
}

type assistantAskRequest struct {
	// Which agent to ask. The console sends the one matching the page the panel
	// is sitting beside; empty means orders, the only one phase 2 ships.
	Agent    string `json:"agent"`
	Question string `json:"question"`
}

// Status lets the console decide what to render before anybody types.
//
// The composer is disabled when this says no, which is the honest thing: a
// field that accepts text and then swallows it is worse than one that says it
// is not connected. The console has shown "Not connected yet" since it was
// built, and this is what finally answers that question at runtime rather than
// at build time.
func (ctl *AssistantController) Status(c *fiber.Ctx) error {
	return c.Status(http.StatusOK).JSON(fiber.Map{
		"code": http.StatusOK, "status": true, "message": "Success",
		"details": fiber.Map{"available": ctl.assistant.Available()},
	})
}

func (ctl *AssistantController) Ask(c *fiber.Ctx) error {
	var req assistantAskRequest
	if err := c.BodyParser(&req); err != nil {
		return assistantRefuse(c, http.StatusBadRequest, "Invalid request body")
	}

	caller, ok := callerFrom(c)
	if !ok {
		// Reachable only while WEB_AUTH_REQUIRED is off, where an untokened
		// request still reaches handlers. Every other endpoint answers such a
		// request; this one must not. Reading a shop's orders through a REST
		// call takes knowing the endpoints and the fields; through an
		// assistant it takes one sentence, so this surface holds the higher
		// bar from its first day rather than inheriting the rollout's.
		return assistantRefuse(c, http.StatusUnauthorized, "Sign in again to use Nearle Buddy.")
	}

	agent := strings.TrimSpace(req.Agent)
	if agent == "" {
		agent = "orders"
	}

	ctx, cancel := services.WithTimeout(c.Context())
	defer cancel()

	answer, err := ctl.assistant.Ask(ctx, agent, req.Question, caller)
	if err != nil {
		// "Not switched on here" is a deployment fact, not a fault, and it gets
		// its own status so the console can disable the composer rather than
		// showing an error the person can do nothing about.
		if errors.Is(err, utils.ErrChatNotConfigured) {
			return c.Status(http.StatusOK).JSON(fiber.Map{
				"code": http.StatusServiceUnavailable, "status": false,
				"message": "Nearle Buddy is not switched on for this deployment.",
			})
		}
		// Asking too fast gets its own status, so the console and whatever
		// watches it can tell "you are going too quickly" apart from "that
		// question was malformed". The message already says how long to wait.
		var tooFast services.ErrTooFast
		if errors.As(err, &tooFast) {
			return assistantRefuse(c, http.StatusTooManyRequests, err.Error())
		}
		return assistantRefuse(c, http.StatusBadRequest, err.Error())
	}

	return c.Status(http.StatusOK).JSON(fiber.Map{
		"code": http.StatusOK, "status": true, "message": "Success", "details": answer,
	})
}

// Approve performs a change the person pressed the button on.
//
// Its own endpoint, not a flag on /ask, because it is a different kind of act:
// no question, no model, no conversation. The card names the action and the
// session names the person, and the registry re-checks both against the live
// database before anything is written.
func (ctl *AssistantController) Approve(c *fiber.Ctx) error {
	var req assistantApproveRequest
	if err := c.BodyParser(&req); err != nil {
		return assistantRefuse(c, http.StatusBadRequest, "Invalid request body")
	}
	if strings.TrimSpace(req.Card) == "" {
		return assistantRefuse(c, http.StatusBadRequest, "Nothing to approve.")
	}

	caller, ok := callerFrom(c)
	if !ok {
		return assistantRefuse(c, http.StatusUnauthorized, "Sign in again to approve this.")
	}

	agent := strings.TrimSpace(req.Agent)
	if agent == "" {
		agent = "orders"
	}

	ctx, cancel := services.WithTimeout(c.Context())
	defer cancel()

	answer, err := ctl.assistant.Approve(ctx, agent, req.Card, caller)
	if err != nil {
		// A refused approval is a business outcome, not a server fault: the card
		// expired, somebody else already approved it, the request was withdrawn.
		// The person needs the reason, and the console renders it beside the
		// card rather than as an error page.
		return assistantRefuse(c, http.StatusConflict, err.Error())
	}

	return c.Status(http.StatusOK).JSON(fiber.Map{
		"code": http.StatusOK, "status": true, "message": "Success", "details": answer,
	})
}

// callerFrom turns a verified session into a tool caller.
//
// The one place the two vocabularies meet. Staff (`issuperadmin`) carry no
// tenant, and the registry lets them through — but a tool that reads a shop's
// data refuses them until they have picked one, because "every tenant at once"
// is not an answer to "what is stuck?".
func callerFrom(c *fiber.Ctx) (tools.Caller, bool) {
	claims, ok := middleware.WebClaimsFrom(c)
	if !ok {
		return tools.Caller{}, false
	}
	return tools.Caller{
		Userid:     claims.Userid,
		Tenantid:   claims.Tenantid,
		Locationid: claims.Locationid,
		Superadmin: claims.Superadmin,
	}, true
}

func assistantRefuse(c *fiber.Ctx, code int, message string) error {
	return c.Status(code).JSON(fiber.Map{"code": code, "status": false, "message": message})
}