import { CalendarDays, FolderKanban, Play, Save, Search, Target } from "lucide-react";
import { FormEvent, useEffect, useMemo, useState } from "react";
import { toast } from "sonner";

import { Badge } from "@/components/ui/badge";
import { Button } from "@/components/ui/button";
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card";
import { Input } from "@/components/ui/input";
import { Textarea } from "@/components/ui/textarea";
import { HelpLink } from "@/components/HelpLink";
import { OrganizationSelect } from "@/components/OrganizationSelect";
import { cn } from "@/lib/utils";
import { createProject, getProjects, lookupTicket, updateProject } from "../api";
import { currentMonth, formatMinutes } from "../format";
import { ticketPattern } from "../timers";
import type { ProjectSummary, TicketMeta } from "../types";

type ProjectsPageProps = {
  onNavigate: (to: string) => void;
  onStartTimer: (ticketNumber: string) => Promise<boolean>;
};

type ProjectForm = {
  ticketNumber: string;
  organizationId: string;
  organizationName: string | null;
  teamspaceProject: string;
  description: string;
  goals: string;
  startsOn: string;
  endsOn: string;
  hourBudget: string;
};

function emptyProjectForm(): ProjectForm {
  return {
    ticketNumber: "",
    organizationId: "",
    organizationName: null,
    teamspaceProject: "",
    description: "",
    goals: "",
    startsOn: "",
    endsOn: "",
    hourBudget: ""
  };
}

function formatHoursInput(minutes?: number | null) {
  if (minutes === null || minutes === undefined) {
    return "";
  }

  return new Intl.NumberFormat("de-DE", { maximumFractionDigits: 2 }).format(minutes / 60);
}

function parseHoursInput(value: string) {
  const trimmed = value.trim();

  if (!trimmed) {
    return null;
  }

  const hours = Number(trimmed.replace(",", "."));

  if (!Number.isFinite(hours) || hours < 0) {
    return undefined;
  }

  return Math.round(hours * 60);
}

function formFromProject(project: ProjectSummary): ProjectForm {
  return {
    ticketNumber: project.ticket_number,
    organizationId: project.organization_id ?? "",
    organizationName: project.organization_name ?? project.customer_name ?? null,
    teamspaceProject: project.teamspace_project ?? "",
    description: project.description,
    goals: project.goals,
    startsOn: project.starts_on ?? "",
    endsOn: project.ends_on ?? "",
    hourBudget: formatHoursInput(project.hour_budget_minutes)
  };
}

export function ProjectsPage({ onNavigate, onStartTimer }: ProjectsPageProps) {
  const [projects, setProjects] = useState<ProjectSummary[]>([]);
  const [loading, setLoading] = useState(true);
  const [form, setForm] = useState<ProjectForm>(() => emptyProjectForm());
  const [lookupStatus, setLookupStatus] = useState<"idle" | "loading" | "found" | "not-found">("idle");
  const [lookupResult, setLookupResult] = useState<TicketMeta | null>(null);
  const [saving, setSaving] = useState(false);
  const [editingProjectId, setEditingProjectId] = useState<string | null>(null);
  const [editForm, setEditForm] = useState<ProjectForm>(() => emptyProjectForm());
  const [savingProjectId, setSavingProjectId] = useState<string | null>(null);

  async function load() {
    setLoading(true);
    try {
      const result = await getProjects();
      setProjects(result.projects);
    } catch (error) {
      toast.error("Projekte konnten nicht geladen werden", {
        description: error instanceof Error ? error.message : "Unbekannter Fehler"
      });
    } finally {
      setLoading(false);
    }
  }

  useEffect(() => {
    void load();
  }, []);

  useEffect(() => {
    const normalizedTicketNumber = form.ticketNumber.trim();

    if (!ticketPattern.test(normalizedTicketNumber)) {
      setLookupStatus("idle");
      setLookupResult(null);
      return;
    }

    let cancelled = false;
    setLookupStatus("loading");

    const timeout = window.setTimeout(async () => {
      try {
        const result = await lookupTicket(normalizedTicketNumber);

        if (cancelled) {
          return;
        }

        setLookupResult(result.ticket);
        setLookupStatus(result.ticket ? "found" : "not-found");

        if (result.ticket?.organization_id) {
          setForm((current) =>
            current.ticketNumber.trim() === normalizedTicketNumber
              ? {
                  ...current,
                  organizationId: result.ticket?.organization_id ?? "",
                  organizationName: result.ticket?.organization_name ?? result.ticket?.customer_name ?? null
                }
              : current
          );
        }
      } catch {
        if (!cancelled) {
          setLookupStatus("idle");
          setLookupResult(null);
        }
      }
    }, 250);

    return () => {
      cancelled = true;
      window.clearTimeout(timeout);
    };
  }, [form.ticketNumber]);

  const organizationLocked = Boolean(lookupResult?.organization_id);
  const openTodos = useMemo(() => projects.reduce((sum, project) => sum + Number(project.open_todos ?? 0), 0), [projects]);
  const billedMinutes = useMemo(() => projects.reduce((sum, project) => sum + Number(project.billed_minutes ?? 0), 0), [projects]);

  async function submitProject(event: FormEvent) {
    event.preventDefault();

    const ticketNumber = form.ticketNumber.trim();

    if (!ticketPattern.test(ticketNumber)) {
      toast.error("Ticketnummer prüfen", {
        description: "Das Format muss Ticket#XXXXXX sein."
      });
      return;
    }

    if (!form.organizationId) {
      toast.error("Organisation wählen", {
        description: "Wenn das Ticket noch keine Stammdaten hat, muss die Organisation gesetzt werden."
      });
      return;
    }

    const hourBudgetMinutes = parseHoursInput(form.hourBudget);

    if (hourBudgetMinutes === undefined) {
      toast.error("Stundenkontingent prüfen", {
        description: "Bitte Stunden als Zahl eintragen, z.B. 12,5."
      });
      return;
    }

    setSaving(true);
    try {
      const result = await createProject({
        ticketNumber,
        organizationId: form.organizationId,
        teamspaceProject: form.teamspaceProject,
        description: form.description,
        goals: form.goals,
        startsOn: form.startsOn || null,
        endsOn: form.endsOn || null,
        hourBudgetMinutes
      });
      toast.success("Projekt angelegt", {
        description: `${result.project.ticket_number} ist jetzt als Consulting-Projekt markiert.`
      });
      setForm(emptyProjectForm());
      setLookupResult(null);
      setLookupStatus("idle");
      await load();
    } catch (error) {
      toast.error("Projekt konnte nicht angelegt werden", {
        description: error instanceof Error ? error.message : "Unbekannter Fehler"
      });
    } finally {
      setSaving(false);
    }
  }

  async function saveProject(project: ProjectSummary) {
    const hourBudgetMinutes = parseHoursInput(editForm.hourBudget);

    if (hourBudgetMinutes === undefined) {
      toast.error("Stundenkontingent prüfen");
      return;
    }

    if (!editForm.organizationId) {
      toast.error("Organisation wählen");
      return;
    }

    setSavingProjectId(project.id);
    try {
      await updateProject(project.id, {
        ticketNumber: editForm.ticketNumber,
        organizationId: editForm.organizationId,
        teamspaceProject: editForm.teamspaceProject,
        description: editForm.description,
        goals: editForm.goals,
        startsOn: editForm.startsOn || null,
        endsOn: editForm.endsOn || null,
        hourBudgetMinutes
      });
      toast.success("Projekt gespeichert");
      setEditingProjectId(null);
      await load();
    } catch (error) {
      toast.error("Projekt konnte nicht gespeichert werden", {
        description: error instanceof Error ? error.message : "Unbekannter Fehler"
      });
    } finally {
      setSavingProjectId(null);
    }
  }

  return (
    <div className="space-y-4">
      <div className="flex flex-col gap-3 lg:flex-row lg:items-end lg:justify-between">
        <div>
          <h2 className="text-xl font-semibold tracking-normal sm:text-2xl">Projekte</h2>
          <p className="text-sm text-muted-foreground">Consulting-Projekte als Erweiterung bestehender oder neuer Tickets.</p>
        </div>
        <div className="grid gap-2 text-sm sm:grid-cols-3">
          <div className="rounded-md border bg-muted/20 px-3 py-2">
            <span className="block text-muted-foreground">Projekte</span>
            <span className="font-semibold">{projects.length}</span>
          </div>
          <div className="rounded-md border bg-muted/20 px-3 py-2">
            <span className="block text-muted-foreground">Abgerechnet</span>
            <span className="font-semibold">{formatMinutes(billedMinutes)}</span>
          </div>
          <div className="rounded-md border bg-muted/20 px-3 py-2">
            <span className="block text-muted-foreground">Offene ToDos</span>
            <span className="font-semibold">{openTodos}</span>
          </div>
        </div>
      </div>

      <Card>
        <CardHeader className="p-4">
          <div className="flex items-start justify-between gap-3">
            <div>
              <CardTitle>Projekt anlegen</CardTitle>
              <CardDescription>Ticketnummer eingeben. Vorhandene Ticketdaten werden automatisch übernommen.</CardDescription>
            </div>
            <HelpLink anchor="projekte" label="Hilfe zu Projekten" />
          </div>
        </CardHeader>
        <CardContent className="px-4 pb-4">
          <form className="space-y-4" onSubmit={submitProject}>
            <div className="grid gap-3 lg:grid-cols-[180px_minmax(240px,1fr)_220px]">
              <div className="space-y-2">
                <label className="text-sm font-medium" htmlFor="project-ticket-number">
                  Ticket
                </label>
                <Input
                  id="project-ticket-number"
                  placeholder="Ticket#123456"
                  value={form.ticketNumber}
                  onChange={(event) =>
                    setForm({
                      ...form,
                      ticketNumber: event.currentTarget.value,
                      organizationId: "",
                      organizationName: null
                    })
                  }
                  required
                />
                {form.ticketNumber && !ticketPattern.test(form.ticketNumber.trim()) ? <p className="text-xs text-destructive">Format: Ticket#XXXXXX</p> : null}
                {lookupStatus === "loading" ? <p className="text-xs text-muted-foreground">Suche Ticket...</p> : null}
                {lookupStatus === "found" ? <p className="text-xs text-muted-foreground">Ticket gefunden. Organisation wird übernommen.</p> : null}
                {lookupStatus === "not-found" ? <p className="text-xs text-muted-foreground">Neues Ticket. Organisation bitte wählen.</p> : null}
              </div>
              <div className="space-y-2">
                <label className="text-sm font-medium">Organisation</label>
                <OrganizationSelect
                  value={form.organizationId}
                  selectedName={form.organizationName}
                  disabled={organizationLocked}
                  onChange={(organization) => setForm({ ...form, organizationId: organization.id, organizationName: organization.name })}
                  required
                />
              </div>
              <div className="space-y-2">
                <label className="text-sm font-medium">Art</label>
                <div className="flex h-9 items-center rounded-lg border bg-muted/30 px-3 text-sm">Consulting</div>
              </div>
            </div>

            <div className="grid gap-3 lg:grid-cols-[minmax(220px,1fr)_140px_140px_160px]">
              <div className="space-y-2">
                <label className="text-sm font-medium" htmlFor="teamspace-project">
                  Teamspace-Projekt
                </label>
                <Input id="teamspace-project" value={form.teamspaceProject} onChange={(event) => setForm({ ...form, teamspaceProject: event.currentTarget.value })} />
              </div>
              <div className="space-y-2">
                <label className="text-sm font-medium" htmlFor="project-starts-on">
                  Zeitraum von
                </label>
                <Input id="project-starts-on" type="date" value={form.startsOn} onChange={(event) => setForm({ ...form, startsOn: event.currentTarget.value })} />
              </div>
              <div className="space-y-2">
                <label className="text-sm font-medium" htmlFor="project-ends-on">
                  Zeitraum bis
                </label>
                <Input id="project-ends-on" type="date" value={form.endsOn} onChange={(event) => setForm({ ...form, endsOn: event.currentTarget.value })} />
              </div>
              <div className="space-y-2">
                <label className="text-sm font-medium" htmlFor="project-budget">
                  Kontingent h
                </label>
                <Input id="project-budget" inputMode="decimal" value={form.hourBudget} onChange={(event) => setForm({ ...form, hourBudget: event.currentTarget.value })} />
              </div>
            </div>

            <div className="grid gap-3 lg:grid-cols-2">
              <div className="space-y-2">
                <label className="text-sm font-medium" htmlFor="project-description">
                  Projektbeschreibung
                </label>
                <Textarea id="project-description" className="min-h-24" value={form.description} onChange={(event) => setForm({ ...form, description: event.currentTarget.value })} />
              </div>
              <div className="space-y-2">
                <label className="text-sm font-medium" htmlFor="project-goals">
                  Ziele
                </label>
                <Textarea id="project-goals" className="min-h-24" value={form.goals} onChange={(event) => setForm({ ...form, goals: event.currentTarget.value })} />
              </div>
            </div>

            <div className="flex justify-end">
              <Button type="submit" disabled={saving}>
                <Save className="size-4" />
                {saving ? "Speichert..." : "Projekt anlegen"}
              </Button>
            </div>
          </form>
        </CardContent>
      </Card>

      <div className="grid gap-3 xl:grid-cols-2">
        {projects.map((project) => {
          const isEditing = editingProjectId === project.id;
          const usedPercent =
            project.hour_budget_minutes && project.hour_budget_minutes > 0
              ? Math.min(100, Math.round(((project.billed_minutes ?? 0) / project.hour_budget_minutes) * 100))
              : null;

          return (
            <Card key={project.id} className="overflow-hidden">
              <CardHeader className="border-b bg-muted/25 p-4">
                <div className="flex items-start justify-between gap-3">
                  <div className="min-w-0">
                    <div className="flex flex-wrap items-center gap-2">
                      <CardTitle className="truncate text-base">{project.ticket_number}</CardTitle>
                      <Badge variant="outline">Projekt</Badge>
                    </div>
                    <CardDescription className="truncate">{project.teamspace_project || project.organization_name || "Ohne Teamspace-Projekt"}</CardDescription>
                  </div>
                  <div className="flex shrink-0 gap-1">
                    <Button type="button" size="sm" variant="secondary" onClick={() => void onStartTimer(project.ticket_number)}>
                      <Play className="size-4" />
                      Session
                    </Button>
                    <Button type="button" size="sm" variant="secondary" onClick={() => onNavigate(`/tickets/${project.ticket_id}?month=${currentMonth()}`)}>
                      <Search className="size-4" />
                      Öffnen
                    </Button>
                  </div>
                </div>
              </CardHeader>
              <CardContent className="space-y-3 p-4">
                {isEditing ? (
                  <div className="space-y-3">
                    <div className="grid gap-3 md:grid-cols-[160px_minmax(200px,1fr)_160px]">
                      <Input value={editForm.ticketNumber} onChange={(event) => setEditForm({ ...editForm, ticketNumber: event.currentTarget.value })} />
                      <OrganizationSelect
                        value={editForm.organizationId}
                        selectedName={editForm.organizationName}
                        onChange={(organization) => setEditForm({ ...editForm, organizationId: organization.id, organizationName: organization.name })}
                        required
                      />
                      <div className="flex h-9 items-center rounded-lg border bg-muted/30 px-3 text-sm">Consulting</div>
                    </div>
                    <Input
                      placeholder="Teamspace-Projekt"
                      value={editForm.teamspaceProject}
                      onChange={(event) => setEditForm({ ...editForm, teamspaceProject: event.currentTarget.value })}
                    />
                    <div className="grid gap-3 md:grid-cols-3">
                      <Input type="date" value={editForm.startsOn} onChange={(event) => setEditForm({ ...editForm, startsOn: event.currentTarget.value })} />
                      <Input type="date" value={editForm.endsOn} onChange={(event) => setEditForm({ ...editForm, endsOn: event.currentTarget.value })} />
                      <Input inputMode="decimal" placeholder="Kontingent h" value={editForm.hourBudget} onChange={(event) => setEditForm({ ...editForm, hourBudget: event.currentTarget.value })} />
                    </div>
                    <Textarea className="min-h-20" value={editForm.description} onChange={(event) => setEditForm({ ...editForm, description: event.currentTarget.value })} />
                    <Textarea className="min-h-20" value={editForm.goals} onChange={(event) => setEditForm({ ...editForm, goals: event.currentTarget.value })} />
                    <div className="flex justify-end gap-2">
                      <Button type="button" variant="ghost" onClick={() => setEditingProjectId(null)}>
                        Abbrechen
                      </Button>
                      <Button type="button" disabled={savingProjectId === project.id} onClick={() => void saveProject(project)}>
                        <Save className="size-4" />
                        Speichern
                      </Button>
                    </div>
                  </div>
                ) : (
                  <>
                    <div className="grid gap-2 text-sm sm:grid-cols-3">
                      <div className="rounded-md border bg-background p-2">
                        <span className="block text-xs text-muted-foreground">Organisation</span>
                        <span className="line-clamp-1 font-medium">{project.organization_name ?? project.customer_name ?? "Keine Organisation"}</span>
                      </div>
                      <div className="rounded-md border bg-background p-2">
                        <span className="block text-xs text-muted-foreground">Zeitraum</span>
                        <span className="font-medium">{project.starts_on || "offen"} - {project.ends_on || "offen"}</span>
                      </div>
                      <div className="rounded-md border bg-background p-2">
                        <span className="block text-xs text-muted-foreground">Kontingent</span>
                        <span className="font-medium">{project.hour_budget_minutes ? formatMinutes(project.hour_budget_minutes) : "offen"}</span>
                      </div>
                    </div>

                    {usedPercent !== null ? (
                      <div className="space-y-1">
                        <div className="flex items-center justify-between text-xs text-muted-foreground">
                          <span>Verbrauch</span>
                          <span>{usedPercent}% · {formatMinutes(project.billed_minutes ?? 0)}</span>
                        </div>
                        <div className="h-2 overflow-hidden rounded-full bg-muted">
                          <div className={cn("h-full rounded-full", usedPercent >= 90 ? "bg-amber-500" : "bg-emerald-500")} style={{ width: `${usedPercent}%` }} />
                        </div>
                      </div>
                    ) : null}

                    <div className="grid gap-3 text-sm md:grid-cols-2">
                      <div>
                        <div className="mb-1 flex items-center gap-2 font-medium">
                          <FolderKanban className="size-4 text-muted-foreground" />
                          Beschreibung
                        </div>
                        <p className="whitespace-pre-wrap text-muted-foreground">{project.description || "Noch keine Beschreibung."}</p>
                      </div>
                      <div>
                        <div className="mb-1 flex items-center gap-2 font-medium">
                          <Target className="size-4 text-muted-foreground" />
                          Ziele
                        </div>
                        <p className="whitespace-pre-wrap text-muted-foreground">{project.goals || "Noch keine Ziele."}</p>
                      </div>
                    </div>

                    <div className="flex flex-wrap items-center justify-between gap-2 border-t pt-3">
                      <div className="flex flex-wrap gap-2 text-xs text-muted-foreground">
                        <Badge variant="secondary">{project.session_count ?? 0} Session(s)</Badge>
                        <Badge variant={(project.open_todos ?? 0) > 0 ? "warning" : "success"}>{project.open_todos ?? 0} offene ToDos</Badge>
                        <span className="inline-flex items-center gap-1">
                          <CalendarDays className="size-3.5" />
                          aktualisiert {new Date(project.updated_at).toLocaleDateString("de-DE")}
                        </span>
                      </div>
                      <Button
                        type="button"
                        size="sm"
                        variant="ghost"
                        onClick={() => {
                          setEditingProjectId(project.id);
                          setEditForm(formFromProject(project));
                        }}
                      >
                        Bearbeiten
                      </Button>
                    </div>
                  </>
                )}
              </CardContent>
            </Card>
          );
        })}
      </div>

      {!loading && projects.length === 0 ? <p className="rounded-md border bg-muted/20 p-6 text-center text-sm text-muted-foreground">Noch keine Projekte angelegt.</p> : null}
    </div>
  );
}