package handlers

import (
	"encoding/json"
	"errors"
	"log"
	"net/http"
	"strconv"

	"github.com/google/uuid"

	"mgit.msbls.de/m/patholo/internal/auth"
	"mgit.msbls.de/m/patholo/internal/services"
)

// dbServices bundles the Phase B services so handlers can stay thin.
// Nil if DATABASE_URL was unset at startup.
type dbServices struct {
	projects       *services.ProjectService
	team           *services.TeamService
	department     *services.DepartmentService
	parties        *services.PartyService
	deadline       *services.DeadlineService
	appointment    *services.AppointmentService
	caldav         *services.CalDAVService
	rules          *services.DeadlineRuleService
	calc           *services.DeadlineCalculator
	users          *services.UserService
	fristenrechner *services.FristenrechnerService
	dashboard      *services.DashboardService
	note           *services.NoteService
	checklistInst  *services.ChecklistInstanceService
	mail           *services.MailService
	invite         *services.InviteService
	agenda         *services.AgendaService
}

var dbSvc *dbServices

// requireDB returns true if the DB-backed services are wired; otherwise
// writes a 503 response and returns false.
func requireDB(w http.ResponseWriter) bool {
	if dbSvc == nil {
		writeJSON(w, http.StatusServiceUnavailable, map[string]string{
			"error": "database not configured — set DATABASE_URL on the server",
		})
		return false
	}
	return true
}

// requireUser pulls the authenticated user UUID from the request context.
func requireUser(w http.ResponseWriter, r *http.Request) (uuid.UUID, bool) {
	uid, ok := auth.UserIDFromContext(r.Context())
	if !ok {
		writeJSON(w, http.StatusUnauthorized, map[string]string{
			"error": "authentication required",
		})
		return uuid.Nil, false
	}
	return uid, true
}

// writeServiceError maps a services error to an HTTP status.
func writeServiceError(w http.ResponseWriter, err error) {
	switch {
	case errors.Is(err, services.ErrNotVisible):
		writeJSON(w, http.StatusNotFound, map[string]string{"error": "not found"})
	case errors.Is(err, services.ErrForbidden):
		writeJSON(w, http.StatusForbidden, map[string]string{"error": err.Error()})
	case errors.Is(err, services.ErrInvalidInput):
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": err.Error()})
	default:
		log.Printf("ERROR service: %v", err)
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": "internal error"})
	}
}

// GET /api/projects — list visible projects.
// Query params: ?type=case&status=active&parent_id=<uuid>&parent_null=1&search=foo
func handleListProjects(w http.ResponseWriter, r *http.Request) {
	if !requireDB(w) {
		return
	}
	uid, ok := requireUser(w, r)
	if !ok {
		return
	}
	q := r.URL.Query()
	filter := services.ProjectFilter{
		Type:   q.Get("type"),
		Status: q.Get("status"),
		Search: q.Get("search"),
	}
	if pidStr := q.Get("parent_id"); pidStr != "" {
		pid, err := uuid.Parse(pidStr)
		if err != nil {
			writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid parent_id"})
			return
		}
		filter.ParentID = &pid
	}
	if q.Get("parent_null") == "1" || q.Get("parent_null") == "true" {
		filter.ParentNullOnly = true
	}
	rows, err := dbSvc.projects.List(r.Context(), uid, filter)
	if err != nil {
		writeServiceError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, rows)
}

// POST /api/projects — also accepts the legacy POST /api/akten body shape
// ({aktenzeichen, owning_office, court_ref}) for the frontend transition.
// aktenzeichen → reference, court_ref → case_number, owning_office is dropped
// (no longer part of the visibility model). Type defaults to 'case'.
func handleCreateProject(w http.ResponseWriter, r *http.Request) {
	if !requireDB(w) {
		return
	}
	uid, ok := requireUser(w, r)
	if !ok {
		return
	}
	// Parse into a loose map so we can accept both old and new shapes.
	var raw map[string]any
	if err := json.NewDecoder(r.Body).Decode(&raw); err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid JSON"})
		return
	}
	input := services.CreateProjektInput{
		Type: services.ProjectTypeCase,
	}
	if v, ok := raw["type"].(string); ok && v != "" {
		input.Type = v
	}
	if v, ok := raw["title"].(string); ok {
		input.Title = v
	}
	// Legacy aktenzeichen → reference; new shape uses reference directly.
	if v, ok := raw["reference"].(string); ok && v != "" {
		input.Reference = &v
	} else if v, ok := raw["aktenzeichen"].(string); ok && v != "" {
		input.Reference = &v
	}
	if v, ok := raw["description"].(string); ok && v != "" {
		input.Description = &v
	}
	if v, ok := raw["status"].(string); ok {
		input.Status = v
	}
	if v, ok := raw["court"].(string); ok && v != "" {
		input.Court = &v
	}
	if v, ok := raw["case_number"].(string); ok && v != "" {
		input.CaseNumber = &v
	} else if v, ok := raw["court_ref"].(string); ok && v != "" {
		input.CaseNumber = &v
	}
	if v, ok := raw["parent_id"].(string); ok && v != "" {
		pid, err := uuid.Parse(v)
		if err != nil {
			writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid parent_id"})
			return
		}
		input.ParentID = &pid
	}
	if v, ok := raw["client_number"].(string); ok && v != "" {
		input.ClientNumber = &v
	}
	if v, ok := raw["matter_number"].(string); ok && v != "" {
		input.MatterNumber = &v
	}
	if v, ok := raw["netdocuments_url"].(string); ok && v != "" {
		input.NetDocumentsURL = &v
	}
	p, err := dbSvc.projects.Create(r.Context(), uid, input)
	if err != nil {
		writeServiceError(w, err)
		return
	}
	writeJSON(w, http.StatusCreated, p)
}

// GET /api/projects/{id}
func handleGetProject(w http.ResponseWriter, r *http.Request) {
	if !requireDB(w) {
		return
	}
	uid, ok := requireUser(w, r)
	if !ok {
		return
	}
	id, err := uuid.Parse(r.PathValue("id"))
	if err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid id"})
		return
	}
	p, err := dbSvc.projects.GetByID(r.Context(), uid, id)
	if err != nil {
		writeServiceError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, p)
}

// GET /api/projects/{id}/children — direct children.
func handleListProjectChildren(w http.ResponseWriter, r *http.Request) {
	if !requireDB(w) {
		return
	}
	uid, ok := requireUser(w, r)
	if !ok {
		return
	}
	id, err := uuid.Parse(r.PathValue("id"))
	if err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid id"})
		return
	}
	rows, err := dbSvc.projects.ListChildren(r.Context(), uid, id)
	if err != nil {
		writeServiceError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, rows)
}

// GET /api/projects/{id}/tree — full subtree depth-first (path-ordered).
func handleGetProjectTree(w http.ResponseWriter, r *http.Request) {
	if !requireDB(w) {
		return
	}
	uid, ok := requireUser(w, r)
	if !ok {
		return
	}
	id, err := uuid.Parse(r.PathValue("id"))
	if err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid id"})
		return
	}
	rows, err := dbSvc.projects.GetTree(r.Context(), uid, id)
	if err != nil {
		writeServiceError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, rows)
}

// GET /api/projects/{id}/ancestors — ancestor chain for breadcrumbs.
func handleListProjectAncestors(w http.ResponseWriter, r *http.Request) {
	if !requireDB(w) {
		return
	}
	uid, ok := requireUser(w, r)
	if !ok {
		return
	}
	id, err := uuid.Parse(r.PathValue("id"))
	if err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid id"})
		return
	}
	rows, err := dbSvc.projects.ListAncestors(r.Context(), uid, id)
	if err != nil {
		writeServiceError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, rows)
}

// PATCH /api/projects/{id}
func handleUpdateProject(w http.ResponseWriter, r *http.Request) {
	if !requireDB(w) {
		return
	}
	uid, ok := requireUser(w, r)
	if !ok {
		return
	}
	id, err := uuid.Parse(r.PathValue("id"))
	if err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid id"})
		return
	}
	var input services.UpdateProjektInput
	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid JSON"})
		return
	}
	p, err := dbSvc.projects.Update(r.Context(), uid, id, input)
	if err != nil {
		writeServiceError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, p)
}

// DELETE /api/projects/{id}
func handleDeleteProject(w http.ResponseWriter, r *http.Request) {
	if !requireDB(w) {
		return
	}
	uid, ok := requireUser(w, r)
	if !ok {
		return
	}
	id, err := uuid.Parse(r.PathValue("id"))
	if err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid id"})
		return
	}
	if err := dbSvc.projects.Delete(r.Context(), uid, id); err != nil {
		writeServiceError(w, err)
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

// GET /api/projects/{id}/events — audit trail with cursor pagination.
func handleListProjectEvents(w http.ResponseWriter, r *http.Request) {
	if !requireDB(w) {
		return
	}
	uid, ok := requireUser(w, r)
	if !ok {
		return
	}
	id, err := uuid.Parse(r.PathValue("id"))
	if err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid id"})
		return
	}
	q := r.URL.Query()
	var before *uuid.UUID
	if b := q.Get("before"); b != "" {
		bu, err := uuid.Parse(b)
		if err != nil {
			writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid before cursor"})
			return
		}
		before = &bu
	}
	limit := 0
	if l := q.Get("limit"); l != "" {
		n, err := strconv.Atoi(l)
		if err != nil || n < 0 {
			writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid limit"})
			return
		}
		limit = n
	}
	rows, err := dbSvc.projects.ListEvents(r.Context(), uid, id, before, limit)
	if err != nil {
		writeServiceError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, rows)
}

// GET /api/projects/{id}/parties
func handleListParties(w http.ResponseWriter, r *http.Request) {
	if !requireDB(w) {
		return
	}
	uid, ok := requireUser(w, r)
	if !ok {
		return
	}
	id, err := uuid.Parse(r.PathValue("id"))
	if err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid id"})
		return
	}
	rows, err := dbSvc.parties.ListForProjekt(r.Context(), uid, id)
	if err != nil {
		writeServiceError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, rows)
}

// POST /api/projects/{id}/parties
func handleCreateParty(w http.ResponseWriter, r *http.Request) {
	if !requireDB(w) {
		return
	}
	uid, ok := requireUser(w, r)
	if !ok {
		return
	}
	id, err := uuid.Parse(r.PathValue("id"))
	if err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid id"})
		return
	}
	var input services.CreateParteiInput
	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid JSON"})
		return
	}
	p, err := dbSvc.parties.Create(r.Context(), uid, id, input)
	if err != nil {
		writeServiceError(w, err)
		return
	}
	writeJSON(w, http.StatusCreated, p)
}

// DELETE /api/parties/{id}
func handleDeleteParty(w http.ResponseWriter, r *http.Request) {
	if !requireDB(w) {
		return
	}
	uid, ok := requireUser(w, r)
	if !ok {
		return
	}
	parteiID, err := uuid.Parse(r.PathValue("id"))
	if err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid id"})
		return
	}
	if err := dbSvc.parties.Delete(r.Context(), uid, parteiID); err != nil {
		writeServiceError(w, err)
		return
	}
	w.WriteHeader(http.StatusNoContent)
}