package controllers

import (
	"encoding/json"
	"os"
	"strconv"
	"strings"
	"time"

	"doormile/constants"
	"doormile/db"
	"doormile/models"
	"doormile/utils"

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

// expressAgentEnabled gates the whole express-batch handoff. Default OFF, so
// deploying this code changes nothing: a bulk create keeps assigning each
// booking inline exactly as before, and no batch event is emitted. Flip
// EXPRESS_AGENT_ENABLED=true ONLY once the ExpressDispatchAgent is confirmed
// running and consuming express.batch_created — otherwise batches would suppress
// inline assignment with nothing to pick them up, and bulk bookings would sit
// unassigned. Read at request time so it can be toggled without a redeploy.
func expressAgentEnabled() bool {
	return strings.EqualFold(os.Getenv("EXPRESS_AGENT_ENABLED"), "true")
}

// expressDispatchSubject is the JetStream subject the ExpressDispatchAgent binds
// to. It must be present on the EXPRESS stream (db/streams.go) before anything
// publishes here — JetStream silently drops messages on uncovered subjects.
const expressDispatchSubject = "express.dispatch_requested"

// publishExpressBatch emits one express.dispatch_requested event per tenant when
// an operator dispatches their pending orders. Best-effort like every publish in
// this codebase: a NATS outage degrades to hand-assignment from the console, it
// never fails the request.
func publishExpressBatch(byTenant map[int][]int) {
	if db.Js == nil {
		if len(byTenant) > 0 {
			utils.Warn("Express: JetStream unavailable, dispatch not handed to agent",
				"tenants", len(byTenant))
		}
		return
	}
	for tenantID, bookingIDs := range byTenant {
		if len(bookingIDs) == 0 {
			continue
		}
		payload := map[string]interface{}{
			"tenantid":    tenantID,
			"booking_ids": bookingIDs,
			"created_at":  time.Now().UnixMilli(),
		}
		data, err := json.Marshal(payload)
		if err != nil {
			utils.Warn("Express: failed to marshal dispatch event", "tenantid", tenantID, "error", err)
			continue
		}
		if _, err := db.Js.Publish(expressDispatchSubject, data); err != nil {
			utils.Warn("Express: failed to publish dispatch event", "tenantid", tenantID, "error", err)
			continue
		}
		utils.Info("Express: published "+expressDispatchSubject,
			"tenantid", tenantID, "bookings", len(bookingIDs))
	}
}

// This file is the internal API surface the ExpressDispatchAgent (logistics-ai)
// uses to run the express-batch flow: read the tenant's available riders, read
// the batch's bookings, and write back the assignments it decided after calling
// the Route Optimization API. All three sit under /internal (InternalKeyAuth),
// never exposed to a console or app token.
//
// The division of labour: the agent decides *who* and *what order* (rider pool +
// routes.workolik). Go stays the single writer of assignment state — the agent
// never writes the DB directly, it posts its decision here and this reuses the
// same transactional assignment path the consoles use.

// DispatchExpressBatch is the manual trigger the console operator hits once a
// batch of express orders has piled up. Orders are created batch by batch (bulk
// create only accumulates them, unassigned); this hands the whole pending set
// for the tenant to the ExpressDispatchAgent in one go — the "take over from
// here" button.
//
// Console auth, tenant-scoped: a client login dispatches only its own pending
// orders; Doormile staff pass ?tenantid= to dispatch for one client. An optional
// body {"booking_ids":[...]} dispatches a chosen subset instead of everything
// pending — always still pinned to the resolved tenant so no cross-tenant id can
// be smuggled in.
func DispatchExpressBatch(c *fiber.Ctx) error {
	tenantID, allowed := effectiveTenantID(c)
	if !allowed {
		return utils.Forbidden(c, "you can only dispatch your own tenant")
	}
	if tenantID == 0 {
		return utils.BadRequest(c, "tenantid is required (staff must pass ?tenantid=)")
	}

	var body struct {
		BookingIDs []int `json:"booking_ids"`
	}
	_ = c.BodyParser(&body) // body is optional

	// Only ever the tenant's own, unassigned, still-pending express orders.
	q := db.DB.Model(&models.PickupBooking{}).
		Where("tenantid = ? AND bookingsource = ? AND assignedmileruserid IS NULL AND status = ?",
			tenantID, constants.BookingSourceExpress, constants.BookingPendingPickup)
	if len(body.BookingIDs) > 0 {
		q = q.Where("bookingid IN ?", body.BookingIDs)
	}

	var bookingIDs []int
	if err := q.Pluck("bookingid", &bookingIDs).Error; err != nil {
		return utils.Internal(c, "failed to gather pending bookings")
	}
	if len(bookingIDs) == 0 {
		return utils.OK(c, fiber.Map{
			"queued":      0,
			"booking_ids": []int{},
			"message":     "no pending express bookings to dispatch",
		})
	}

	publishExpressBatch(map[int][]int{tenantID: bookingIDs})

	resp := fiber.Map{
		"queued":      len(bookingIDs),
		"booking_ids": bookingIDs,
	}
	if !expressAgentEnabled() {
		// The batch was published, but with the flag off the bulk path may have
		// already assigned these inline and the agent may not be consuming — make
		// that visible rather than implying work was dispatched.
		resp["warning"] = "EXPRESS_AGENT_ENABLED is off; the agent may not be consuming this event"
	}
	return utils.OK(c, resp)
}

// GetExpressRiders returns a tenant's riders that are free to take work, with the
// location and hub the agent needs to distribute stops. Optional ?city= narrows
// to one operating zone (applocationid) so a Coimbatore batch is never handed to
// a Nagercoil rider.
func GetExpressRiders(c *fiber.Ctx) error {
	tenantID := c.QueryInt("tenantid", 0)
	if tenantID == 0 {
		return utils.BadRequest(c, "tenantid is required")
	}

	type riderRow struct {
		Userid             int     `json:"miler_user_id"`
		Displayname        string  `json:"displayname"`
		Phone              string  `json:"phone"`
		Currentlatitude    float64 `json:"latitude"`
		Currentlongitude   float64 `json:"longitude"`
		Hubid              *int    `json:"hubid"`
		Applocationid      int     `json:"applocationid"`
		Availabilitystatus string  `json:"availabilitystatus"`
		Devicetoken        string  `json:"has_device_token"`
	}

	q := db.DB.Table("milerprofiles AS mp").
		Select(`mp.userid, mp.displayname, mp.phone, mp.currentlatitude,
		        mp.currentlongitude, mp.hubid, mp.applocationid,
		        mp.availabilitystatus, mp.device_token`).
		Joins("JOIN appusers AS u ON u.userid = mp.userid").
		Where("u.tenantid = ? AND u.roleid = ? AND mp.availabilitystatus = ?",
			tenantID, 5, constants.MilerAvailable)

	if city := c.QueryInt("city", 0); city != 0 {
		q = q.Where("mp.applocationid = ?", city)
	}

	var rows []riderRow
	if err := q.Scan(&rows).Error; err != nil {
		return utils.Internal(c, "failed to load riders")
	}

	// Expose only whether a device token exists, never the token itself.
	out := make([]fiber.Map, 0, len(rows))
	for _, r := range rows {
		out = append(out, fiber.Map{
			"miler_user_id":      r.Userid,
			"displayname":        r.Displayname,
			"phone":              r.Phone,
			"latitude":           r.Currentlatitude,
			"longitude":          r.Currentlongitude,
			"hubid":              r.Hubid,
			"applocationid":      r.Applocationid,
			"availabilitystatus": r.Availabilitystatus,
			"has_device_token":   r.Devicetoken != "",
		})
	}
	return c.JSON(fiber.Map{"success": true, "riders": out, "total": len(out)})
}

// GetExpressBookings returns the coordinates and kitchen for a set of booking
// ids — everything the agent needs to feed the optimizer, and nothing it does
// not. ?ids=1,2,3.
func GetExpressBookings(c *fiber.Ctx) error {
	idsParam := c.Query("ids")
	if idsParam == "" {
		return utils.BadRequest(c, "ids is required, e.g. ?ids=1,2,3")
	}

	ids := make([]int, 0)
	for _, part := range strings.Split(idsParam, ",") {
		part = strings.TrimSpace(part)
		if part == "" {
			continue
		}
		n, err := strconv.Atoi(part)
		if err != nil {
			return utils.BadRequest(c, "ids must be a comma-separated list of integers")
		}
		ids = append(ids, n)
	}
	if len(ids) == 0 {
		return utils.BadRequest(c, "ids is required")
	}

	type bookingRow struct {
		Bookingid           int     `json:"booking_id"`
		Bookingno           string  `json:"booking_no"`
		Tenantid            *int    `json:"tenantid"`
		Tenantlocationid    *int    `json:"tenantlocationid"`
		Pickuplatitude      float64 `json:"pickuplatitude"`
		Pickuplongitude     float64 `json:"pickuplongitude"`
		Deliverylatitude    float64 `json:"deliverylatitude"`
		Deliverylongitude   float64 `json:"deliverylongitude"`
		Pickuppincode       string  `json:"pickuppincode"`
		Deliverypincode     string  `json:"deliverypincode"`
		Status              string  `json:"status"`
		Assignedmileruserid *int    `json:"assignedmileruserid"`
	}

	var rows []bookingRow
	if err := db.DB.Model(&models.PickupBooking{}).
		Select(`bookingid, bookingno, tenantid, tenantlocationid,
		        pickuplatitude, pickuplongitude, deliverylatitude, deliverylongitude,
		        pickuppincode, deliverypincode, status, assignedmileruserid`).
		Where("bookingid IN ?", ids).
		Scan(&rows).Error; err != nil {
		return utils.Internal(c, "failed to load bookings")
	}

	return c.JSON(fiber.Map{"success": true, "bookings": rows, "total": len(rows)})
}

// AssignExpressBatch writes the agent's decided assignments. Body:
//
//	{ "assignments": [ {booking_id, miler_user_id, step, previouskms,
//	                    cumulativekms, etaminutes, cumulativeeta}, ... ] }
//
// Each row is assigned in its own transaction with its sequence already set, and
// each miler is notified once for the whole batch. Per-row results mirror the
// bulk-create shape so a single bad booking id never fails the batch.
func AssignExpressBatch(c *fiber.Ctx) error {
	var req struct {
		Assignments []ExpressStop `json:"assignments"`
	}
	if err := c.BodyParser(&req); err != nil {
		return utils.BadRequest(c, "invalid request body")
	}
	if len(req.Assignments) == 0 {
		return utils.BadRequest(c, "assignments is required and must not be empty")
	}

	// Guard against writing to a booking that is not actually the tenant's or is
	// already assigned — the agent is trusted but the writeback must still be the
	// place assignment invariants are enforced, not the agent.
	bookingIDs := make([]int, 0, len(req.Assignments))
	for _, a := range req.Assignments {
		bookingIDs = append(bookingIDs, a.BookingID)
	}
	assignable := map[int]bool{}
	var existing []struct {
		Bookingid           int
		Assignedmileruserid *int
		Status              string
	}
	db.DB.Model(&models.PickupBooking{}).
		Select("bookingid, assignedmileruserid, status").
		Where("bookingid IN ?", bookingIDs).
		Scan(&existing)
	for _, b := range existing {
		assignable[b.Bookingid] = b.Assignedmileruserid == nil &&
			b.Status != constants.BookingCancelled
	}

	toAssign := make([]ExpressStop, 0, len(req.Assignments))
	results := make([]ExpressAssignResult, 0, len(req.Assignments))
	for _, a := range req.Assignments {
		if !assignable[a.BookingID] {
			results = append(results, ExpressAssignResult{
				BookingID: a.BookingID, MilerUserID: a.MilerUserID,
				Success: false, Error: "booking already assigned or not eligible"})
			continue
		}
		toAssign = append(toAssign, a)
	}

	results = append(results, assignExpressStops(toAssign)...)

	assigned := 0
	for _, r := range results {
		if r.Success {
			assigned++
		}
	}
	return c.JSON(fiber.Map{
		"success":  true,
		"assigned": assigned,
		"total":    len(req.Assignments),
		"results":  results,
	})
}