package httpapi

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"strings"
	"time"

	"calllinesystem/server/internal/domain"
	"calllinesystem/server/internal/model"
	"calllinesystem/server/internal/security"

	"gorm.io/gorm"
)

func (s *Server) publicStatus(w http.ResponseWriter, r *http.Request) {
	token := strings.TrimSpace(r.PathValue("token"))
	if (len(token) < 40 || len(token) > 128) && !(s.config.Environment == "development" && strings.HasPrefix(token, "demo-visitor-") && len(token) <= 64) {
		writeError(w, &apiError{Status: http.StatusNotFound, Code: "STATUS_NOT_FOUND", Message: "排队状态不存在或链接已失效"})
		return
	}
	var ticket model.QueueTicket
	err := s.db.WithContext(r.Context()).Where("public_token_hash = ?", security.HashToken(token)).First(&ticket).Error
	if err != nil {
		writeError(w, mapNotFound(err, "STATUS_NOT_FOUND", "排队状态不存在或链接已失效"))
		return
	}
	view, err := s.publicStatusView(r.Context(), ticket)
	if err != nil {
		writeError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, view)
}

func (s *Server) publicProjects(w http.ResponseWriter, r *http.Request) {
	var projects []model.Project
	if err := s.db.WithContext(r.Context()).
		Where("status = ?", model.ProjectRunning).
		Order("name ASC").Find(&projects).Error; err != nil {
		writeError(w, err)
		return
	}
	views := make([]map[string]any, 0, len(projects))
	for _, project := range projects {
		views = append(views, map[string]any{
			"id": project.ID, "name": project.Name, "status": project.Status,
			"visitor_notice": project.VisitorNotice,
			"min_party_size": project.MinPartySize, "max_party_size": project.MaxPartySize,
		})
	}
	writeJSON(w, http.StatusOK, map[string]any{"projects": views})
}

func (s *Server) publicCreateTicket(w http.ResponseWriter, r *http.Request) {
	projectID := r.PathValue("id")
	if err := validateUUID(projectID); err != nil {
		writeError(w, err)
		return
	}
	if s.publicTicketLimiter != nil {
		if allowed, retry := s.publicTicketLimiter.allow("ip:" + publicQueryClientKey(r)); !allowed {
			writePublicTicketRateLimit(w, retry)
			return
		}
	}
	var actor model.User
	if err := s.db.WithContext(r.Context()).Where("username = ?", model.PublicVisitorUsername).First(&actor).Error; err != nil {
		writeError(w, err)
		return
	}
	s.createTicketForActor(w, r, actor.ID, true)
}

type publicPhoneQueryRequest struct {
	Phone string `json:"phone"`
}

// publicStatusByPhone is a temporary operational-test flow. It must be
// replaced by OTP or an external identity provider before production use.
func (s *Server) publicStatusByPhone(w http.ResponseWriter, r *http.Request) {
	if s.config.Environment == "production" {
		writeError(w, &apiError{Status: http.StatusNotFound, Code: "STATUS_NOT_FOUND", Message: "排队状态不存在或链接已失效"})
		return
	}
	s.statusByPhone(w, r, true)
}

func (s *Server) statusByPhone(w http.ResponseWriter, r *http.Request, limitByClientIP bool) {
	if limitByClientIP && s.publicQueryLimiter != nil {
		if allowed, retry := s.publicQueryLimiter.allow("ip:" + publicQueryClientKey(r)); !allowed {
			writePublicQueryRateLimit(w, retry)
			return
		}
	}

	var input publicPhoneQueryRequest
	if err := decodeJSON(r, &input); err != nil {
		writeError(w, err)
		return
	}
	phone, err := security.NormalizePhone(input.Phone)
	if err != nil {
		writeError(w, &apiError{Status: http.StatusUnprocessableEntity, Code: "INVALID_PHONE", Message: "请输入有效的手机号"})
		return
	}
	phoneDigest := s.cipher.Digest(phone)
	if s.publicQueryLimiter != nil {
		if allowed, retry := s.publicQueryLimiter.allow("phone:" + phoneDigest); !allowed {
			writePublicQueryRateLimit(w, retry)
			return
		}
	}

	var tickets []model.QueueTicket
	activeSessionStatuses := []string{"RUNNING", "PAUSED"}
	if err := s.db.WithContext(r.Context()).Model(&model.QueueTicket{}).
		Joins("JOIN projects ON projects.id = queue_tickets.project_id").
		Joins("JOIN queue_sessions ON queue_sessions.id = queue_tickets.queue_session_id AND queue_sessions.project_id = queue_tickets.project_id").
		Where("queue_tickets.phone_hmac = ? AND queue_tickets.status IN ? AND queue_sessions.status IN ? AND projects.status IN ?",
			phoneDigest,
			[]string{model.TicketWaiting, model.TicketCalled, model.TicketArrived},
			activeSessionStatuses,
			[]string{model.ProjectRunning, model.ProjectPaused}).
		Where("queue_sessions.business_date = (? AT TIME ZONE projects.timezone)::date", s.now()).
		Order("projects.name ASC, queue_tickets.ticket_number ASC").
		Find(&tickets).Error; err != nil {
		writeError(w, err)
		return
	}

	views := make([]map[string]any, 0, len(tickets))
	for _, ticket := range tickets {
		view, err := s.publicStatusView(r.Context(), ticket)
		if err != nil {
			writeError(w, err)
			return
		}
		views = append(views, view)
	}
	writeJSON(w, http.StatusOK, map[string]any{"tickets": views})
}

func publicQueryClientKey(r *http.Request) string {
	if ip := remoteIP(r); ip != nil {
		return *ip
	}
	return "unknown"
}

func writePublicQueryRateLimit(w http.ResponseWriter, retry time.Duration) {
	seconds := int((retry + time.Second - 1) / time.Second)
	if seconds < 1 {
		seconds = 1
	}
	w.Header().Set("Retry-After", fmt.Sprintf("%d", seconds))
	writeError(w, &apiError{Status: http.StatusTooManyRequests, Code: "PUBLIC_QUERY_RATE_LIMITED", Message: "查询次数过多，请稍后再试"})
}

func writePublicTicketRateLimit(w http.ResponseWriter, retry time.Duration) {
	seconds := int((retry + time.Second - 1) / time.Second)
	if seconds < 1 {
		seconds = 1
	}
	w.Header().Set("Retry-After", fmt.Sprintf("%d", seconds))
	writeError(w, &apiError{Status: http.StatusTooManyRequests, Code: "PUBLIC_TICKET_RATE_LIMITED", Message: "取号次数过多，请稍后再试"})
}

func (s *Server) publicStatusView(ctx context.Context, ticket model.QueueTicket) (map[string]any, error) {
	var project model.Project
	var session model.QueueSession
	if err := s.db.WithContext(ctx).First(&project, "id = ?", ticket.ProjectID).Error; err != nil {
		return nil, err
	}
	if err := s.db.WithContext(ctx).First(&session, "id = ? AND project_id = ?", ticket.QueueSessionID, ticket.ProjectID).Error; err != nil {
		return nil, err
	}
	experiencedPeople, err := s.displayedExperiencedPeople(ctx, project, &session)
	if err != nil {
		return nil, err
	}
	phoneSuffix, err := s.ticketPhoneLast4(ticket)
	if err != nil {
		return nil, err
	}
	ticketsAhead := 0
	peopleAhead := 0
	if ticket.Status == model.TicketWaiting {
		var totals ticketPeopleTotals
		if err := s.db.WithContext(ctx).Model(&model.QueueTicket{}).
			Select("count(*) AS ticket_count, COALESCE(sum(party_size), 0) AS people_count").
			Where("project_id = ? AND queue_session_id = ? AND status = ? AND ticket_number < ?",
				ticket.ProjectID, ticket.QueueSessionID, model.TicketWaiting, ticket.TicketNumber).Scan(&totals).Error; err != nil {
			return nil, err
		}
		ticketsAhead = int(totals.TicketCount)
		peopleAhead = int(totals.PeopleCount)
	}
	var latestCalledTicket struct {
		DisplayNumber string `gorm:"column:display_number"`
	}
	latestCalledNumber := any(nil)
	if err := s.db.WithContext(ctx).Model(&model.QueueTicket{}).
		Select("display_number").
		Where("project_id = ? AND queue_session_id = ? AND called_at IS NOT NULL", ticket.ProjectID, ticket.QueueSessionID).
		Order("called_at DESC, ticket_number DESC").First(&latestCalledTicket).Error; err != nil && !errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, err
	} else if latestCalledTicket.DisplayNumber != "" {
		latestCalledNumber = latestCalledTicket.DisplayNumber
	}
	eta, err := domain.CalculateETA(domain.ETAInput{
		PeopleAhead: peopleAhead, IntervalPerPerson: time.Duration(project.ETAIntervalSeconds) * time.Second,
		Running: project.Status == model.ProjectRunning && session.Status == "RUNNING" && ticket.Status == model.TicketWaiting,
	})
	if err != nil {
		return nil, err
	}
	if ticket.Status != model.TicketWaiting {
		eta = domain.ETAResult{Available: false, Reason: "ticket_not_waiting"}
	}
	return map[string]any{
		"ticket_number": ticket.DisplayNumber, "display_number": ticket.DisplayNumber,
		"project_name": project.Name, "status": ticket.Status, "party_size": ticket.PartySize, "phone_last4": phoneSuffix, "estimated_wait": eta,
		"visitor_notice":     project.VisitorNotice,
		"experienced_people": experiencedPeople,
		"last_updated_at":    s.now(), "called_at": ticket.CalledAt,
		"ticket": map[string]any{
			"display_number": ticket.DisplayNumber, "status": ticket.Status, "party_size": ticket.PartySize, "joined_at": ticket.JoinedAt,
			"called_at": ticket.CalledAt, "arrived_at": ticket.ArrivedAt, "completed_at": ticket.CompletedAt, "missed_at": ticket.MissedAt,
		},
		"project":       map[string]any{"id": project.ID, "name": project.Name, "status": project.Status},
		"tickets_ahead": ticketsAhead, "people_ahead": peopleAhead, "queue_position": queuePosition(ticket.Status, ticketsAhead),
		"latest_called_number": latestCalledNumber,
		"eta":                  eta, "revision": session.Revision, "server_time": s.now(),
	}, nil
}

func queuePosition(status string, ticketsAhead int) any {
	if status != model.TicketWaiting {
		return nil
	}
	return ticketsAhead + 1
}

// displayTicketDTO is the complete public ticket shape for a display. Keeping
// this separate from staff ticketView makes it impossible to accidentally
// serialize honorifics, encrypted contact fields, internal IDs or timestamps.
type displayTicketDTO struct {
	TicketNumber  string `json:"ticket_number"`
	DisplayNumber string `json:"display_number"`
	Status        string `json:"status"`
	PartySize     int    `json:"party_size"`
}

type displayBatchDTO struct {
	BatchNumber    int                `json:"batch_number"`
	Sequence       int                `json:"sequence"`
	Status         string             `json:"status"`
	CallMode       string             `json:"call_mode"`
	RequestedCount int                `json:"requested_count"`
	TicketCount    int                `json:"ticket_count"`
	PeopleCount    int                `json:"people_count"`
	CalledAt       time.Time          `json:"called_at"`
	Tickets        []displayTicketDTO `json:"tickets"`
}

type displayProjectDTO struct {
	ID     string `json:"id"`
	Name   string `json:"name"`
	Status string `json:"status"`
}

type displaySnapshotDTO struct {
	ProjectName        string            `json:"project_name"`
	Status             string            `json:"status"`
	Project            displayProjectDTO `json:"project"`
	Revision           int64             `json:"revision"`
	WaitingCount       int64             `json:"waiting_count"`
	WaitingTicketCount int64             `json:"waiting_ticket_count"`
	WaitingPeopleCount int64             `json:"waiting_people_count"`
	ExperiencedPeople  int64             `json:"experienced_people"`
	CurrentBatch       *displayBatchDTO  `json:"current_batch"`
	RecentBatches      []displayBatchDTO `json:"recent_batches"`
	EstimatedWait      domain.ETAResult  `json:"estimated_wait"`
	ServerTime         time.Time         `json:"server_time"`
	LastUpdatedAt      time.Time         `json:"last_updated_at"`
}

func normalizeDisplayProjectCode(value string) (string, bool) {
	code := strings.ToUpper(strings.TrimSpace(value))
	if !projectCodePattern.MatchString(code) {
		return "", false
	}
	return code, true
}

func (s *Server) displaySnapshot(w http.ResponseWriter, r *http.Request) {
	identifier := strings.TrimSpace(r.PathValue("token"))
	var project model.Project
	var err error
	if code, ok := normalizeDisplayProjectCode(identifier); ok {
		err = s.db.WithContext(r.Context()).Where("code = ?", code).First(&project).Error
	} else {
		if len(identifier) < 40 || len(identifier) > 128 {
			writeError(w, &apiError{Status: http.StatusNotFound, Code: "DISPLAY_NOT_FOUND", Message: "公示屏绑定不存在"})
			return
		}
		err = s.db.WithContext(r.Context()).Where("display_token_hash = ?", security.HashToken(identifier)).First(&project).Error
	}
	if err != nil {
		writeError(w, mapNotFound(err, "DISPLAY_NOT_FOUND", "公示屏绑定不存在"))
		return
	}
	session, err := s.currentQueueSession(s.db.WithContext(r.Context()), project)
	if errors.Is(err, gorm.ErrRecordNotFound) {
		experiencedPeople, metricErr := s.displayedExperiencedPeople(r.Context(), project, nil)
		if metricErr != nil {
			writeError(w, metricErr)
			return
		}
		writeJSON(w, http.StatusOK, displaySnapshotDTO{
			ProjectName: project.Name, Status: project.Status,
			Project:           displayProjectDTO{ID: project.ID, Name: project.Name, Status: project.Status},
			ExperiencedPeople: experiencedPeople, RecentBatches: []displayBatchDTO{}, EstimatedWait: domain.ETAResult{Available: false, Reason: "queue_not_running"},
			ServerTime: s.now(), LastUpdatedAt: project.UpdatedAt,
		})
		return
	}
	if err != nil {
		writeError(w, err)
		return
	}
	waiting, err := queueTotals(s.db.WithContext(r.Context()), project.ID, session.ID, model.TicketWaiting)
	if err != nil {
		writeError(w, err)
		return
	}
	batch, err := s.currentDisplayBatch(r.Context(), project.ID, session.ID)
	if err != nil {
		writeError(w, err)
		return
	}
	recentBatches, err := s.recentDisplayBatches(r, project.ID, session.ID)
	if err != nil {
		writeError(w, err)
		return
	}
	var lastWaiting model.QueueTicket
	lastWaitingErr := s.db.WithContext(r.Context()).Select("id", "party_size").
		Where("project_id = ? AND queue_session_id = ? AND status = ?", project.ID, session.ID, model.TicketWaiting).
		Order("ticket_number DESC").First(&lastWaiting).Error
	if lastWaitingErr != nil && !errors.Is(lastWaitingErr, gorm.ErrRecordNotFound) {
		writeError(w, lastWaitingErr)
		return
	}
	peopleAhead := int(waiting.PeopleCount)
	if lastWaitingErr == nil {
		peopleAhead = max(0, peopleAhead-lastWaiting.PartySize)
	}
	estimatedWait, err := domain.CalculateETA(domain.ETAInput{
		PeopleAhead: peopleAhead, IntervalPerPerson: time.Duration(project.ETAIntervalSeconds) * time.Second,
		Running: project.Status == model.ProjectRunning && session.Status == "RUNNING" && waiting.TicketCount > 0,
	})
	if err != nil {
		writeError(w, err)
		return
	}
	experiencedPeople, err := s.displayedExperiencedPeople(r.Context(), project, &session)
	if err != nil {
		writeError(w, err)
		return
	}
	lastUpdated := project.UpdatedAt
	if session.UpdatedAt.After(lastUpdated) {
		lastUpdated = session.UpdatedAt
	}
	writeJSON(w, http.StatusOK, displaySnapshotDTO{
		ProjectName: project.Name, Status: project.Status,
		Project:  displayProjectDTO{ID: project.ID, Name: project.Name, Status: project.Status},
		Revision: session.Revision, WaitingCount: waiting.TicketCount,
		WaitingTicketCount: waiting.TicketCount, WaitingPeopleCount: waiting.PeopleCount,
		ExperiencedPeople: experiencedPeople, CurrentBatch: batch, RecentBatches: recentBatches,
		EstimatedWait: estimatedWait, ServerTime: s.now(), LastUpdatedAt: lastUpdated,
	})
}

func (s *Server) currentDisplayBatch(ctx context.Context, projectID, sessionID string) (*displayBatchDTO, error) {
	var batch model.CallBatch
	err := s.db.WithContext(ctx).Where("project_id = ? AND queue_session_id = ? AND status = 'CALLED'", projectID, sessionID).
		Order("batch_sequence DESC").First(&batch).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	tickets, err := displayBatchTickets(s.db.WithContext(ctx), batch.ID, projectID, true)
	if err != nil {
		return nil, err
	}
	view := newDisplayBatchDTO(batch, tickets)
	return &view, nil
}

func (s *Server) recentDisplayBatches(r *http.Request, projectID, sessionID string) ([]displayBatchDTO, error) {
	var batches []model.CallBatch
	if err := s.db.WithContext(r.Context()).Where("project_id = ? AND queue_session_id = ? AND status = 'COMPLETED'", projectID, sessionID).
		Order("batch_sequence DESC").Limit(5).Find(&batches).Error; err != nil {
		return nil, err
	}
	views := make([]displayBatchDTO, 0, len(batches))
	for _, batch := range batches {
		tickets, err := displayBatchTickets(s.db.WithContext(r.Context()), batch.ID, projectID, false)
		if err != nil {
			return nil, err
		}
		views = append(views, newDisplayBatchDTO(batch, tickets))
	}
	return views, nil
}

func displayBatchTickets(db *gorm.DB, batchID, projectID string, calledOnly bool) ([]displayTicketDTO, error) {
	query := db.Table("queue_tickets").
		Select("queue_tickets.display_number, queue_tickets.status, queue_tickets.party_size").
		Joins("JOIN call_batch_tickets cbt ON cbt.ticket_id = queue_tickets.id AND cbt.project_id = queue_tickets.project_id").
		Where("cbt.call_batch_id = ? AND cbt.project_id = ?", batchID, projectID).
		Order("cbt.position ASC")
	if calledOnly {
		query = query.Where("queue_tickets.status = ?", model.TicketCalled)
	}
	type row struct {
		DisplayNumber string
		Status        string
		PartySize     int
	}
	var rows []row
	if err := query.Scan(&rows).Error; err != nil {
		return nil, err
	}
	tickets := make([]displayTicketDTO, 0, len(rows))
	for _, item := range rows {
		tickets = append(tickets, displayTicketDTO{
			TicketNumber: item.DisplayNumber, DisplayNumber: item.DisplayNumber, Status: item.Status, PartySize: item.PartySize,
		})
	}
	return tickets, nil
}

func newDisplayBatchDTO(batch model.CallBatch, tickets []displayTicketDTO) displayBatchDTO {
	return displayBatchDTO{
		BatchNumber: batch.BatchSequence, Sequence: batch.BatchSequence, Status: batch.Status,
		CallMode: batch.CallMode, RequestedCount: batch.RequestedCount,
		TicketCount: batch.TicketCount, PeopleCount: batch.PeopleCount,
		CalledAt: batch.CalledAt, Tickets: tickets,
	}
}

func publicDisplayProjectView(project map[string]any) map[string]any {
	return map[string]any{
		"id":                   project["id"],
		"name":                 project["name"],
		"status":               project["status"],
		"waiting_count":        project["waiting_count"],
		"waiting_ticket_count": project["waiting_ticket_count"],
		"waiting_people_count": project["waiting_people_count"],
		"issued_ticket_count":  project["issued_ticket_count"],
		"latest_ticket_number": project["latest_ticket_number"],
		"experienced_people":   project["experienced_people"],
		"current_batch":        project["current_batch"],
		"estimated_wait":       project["estimated_wait"],
		"last_updated_at":      project["last_updated_at"],
	}
}

func (s *Server) displayOverview(w http.ResponseWriter, r *http.Request) {
	var projects []model.Project
	if err := s.db.WithContext(r.Context()).Order("name ASC").Find(&projects).Error; err != nil {
		writeError(w, err)
		return
	}
	views := make([]map[string]any, 0, len(projects))
	for _, project := range projects {
		projection, _, _, _, _, err := s.adminProjectProjection(r.Context(), project)
		if err != nil {
			writeError(w, err)
			return
		}
		views = append(views, publicDisplayProjectView(projection))
	}
	writeJSON(w, http.StatusOK, map[string]any{"projects": views, "server_time": s.now()})
}

func (s *Server) events(w http.ResponseWriter, r *http.Request) {
	projectID := strings.TrimSpace(r.URL.Query().Get("project_id"))
	if err := validateUUID(projectID); err != nil {
		writeError(w, err)
		return
	}
	if err := s.authorizeProject(r.Context(), projectID); err != nil {
		writeError(w, err)
		return
	}
	flusher, ok := w.(http.Flusher)
	if !ok {
		writeError(w, fmt.Errorf("streaming unsupported"))
		return
	}
	w.Header().Set("Content-Type", "text/event-stream")
	w.Header().Set("Cache-Control", "no-cache, no-transform")
	w.Header().Set("Connection", "keep-alive")
	w.Header().Set("X-Accel-Buffering", "no")
	_, _ = fmt.Fprint(w, "retry: 5000\n\n")
	flusher.Flush()

	events, unsubscribe := s.hub.subscribe(projectID)
	defer unsubscribe()
	keepAlive := time.NewTicker(15 * time.Second)
	defer keepAlive.Stop()
	for {
		select {
		case <-r.Context().Done():
			return
		case body := <-events:
			_, _ = fmt.Fprintf(w, "event: queue\ndata: %s\n\n", body)
			flusher.Flush()
		case <-keepAlive.C:
			_, _ = fmt.Fprint(w, ": keep-alive\n\n")
			flusher.Flush()
		}
	}
}