"use client";

import * as React from "react";
import { Loader2, Send, Sparkles, X } from "lucide-react";

import { Button } from "@/components/ui/button";
import { Input } from "@/components/ui/input";
import { cn } from "@/lib/utils";
import { api } from "@/lib/trpc";
import {
  Sheet,
  SheetContent,
  SheetHeader,
  SheetTitle,
  SheetDescription,
} from "@/components/ui/sheet";

type ChatRole = "user" | "assistant";

type ChatMessage = {
  id: string;
  role: ChatRole;
  content: string;
};

function TypingDots() {
  return (
    <div className="flex items-center gap-1.5 px-1 py-2" aria-hidden>
      {[0, 1, 2].map((i) => (
        <span
          key={i}
          className="inline-block h-2 w-2 animate-bounce rounded-full bg-muted-foreground/70"
          style={{ animationDelay: `${i * 0.15}s` }}
        />
      ))}
    </div>
  );
}

export function OpsCopilotPanel({
  workspaceSlug,
  open,
  onOpenChange,
}: {
  workspaceSlug: string;
  open: boolean;
  onOpenChange: (open: boolean) => void;
}) {
  const [messages, setMessages] = React.useState<ChatMessage[]>([]);
  const [input, setInput] = React.useState("");
  const [draftOpen, setDraftOpen] = React.useState(false);
  const [draftPlanSlug, setDraftPlanSlug] = React.useState("");
  const [draftEpicSlug, setDraftEpicSlug] = React.useState("");
  const [draftSlug, setDraftSlug] = React.useState("");
  const [draftTitle, setDraftTitle] = React.useState("");
  const [draftBody, setDraftBody] = React.useState("");
  const bottomRef = React.useRef<HTMLDivElement>(null);

  const copilotMut = api.opsCopilot.generateText.useMutation({
    onSuccess: (data) => {
      setMessages((prev) => [
        ...prev,
        { id: crypto.randomUUID(), role: "assistant", content: data.text },
      ]);
    },
  });

  const createTaskMut = api.backlog.createTask.useMutation({
    onSuccess: () => {
      setDraftOpen(false);
      setDraftPlanSlug("");
      setDraftEpicSlug("");
      setDraftSlug("");
      setDraftTitle("");
      setDraftBody("");
    },
  });

  React.useEffect(() => {
    bottomRef.current?.scrollIntoView({ behavior: "smooth" });
  }, [messages, copilotMut.isPending]);

  const send = React.useCallback(() => {
    const trimmed = input.trim();
    if (!trimmed || copilotMut.isPending) return;
    if (!workspaceSlug) return;
    const userMsg: ChatMessage = {
      id: crypto.randomUUID(),
      role: "user",
      content: trimmed,
    };
    const next = [...messages, userMsg];
    setMessages(next);
    setInput("");
    const history = next.slice(0, -1).map((m) => ({
      role: m.role,
      content: m.content,
    }));
    copilotMut.mutate({
      workspace: workspaceSlug,
      prompt: trimmed,
      messages: history.length > 0 ? history : undefined,
    });
  }, [input, copilotMut, messages, workspaceSlug]);

  const onKeyDown = (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
    if (e.key === "Enter" && !e.shiftKey) {
      e.preventDefault();
      send();
    }
  };

  const handleDraftTask = () => {
    if (!workspaceSlug) return;
    if (!draftPlanSlug.trim() || !draftEpicSlug.trim() || !draftSlug.trim() || !draftTitle.trim()) {
      return;
    }
    createTaskMut.mutate({
      workspace: workspaceSlug,
      planSlug: draftPlanSlug.trim().toLowerCase(),
      epicSlug: draftEpicSlug.trim().toLowerCase(),
      slug: draftSlug.trim().toLowerCase(),
      title: draftTitle.trim(),
      bodyMarkdown: draftBody.trim() || undefined,
    });
  };

  const isBusy = copilotMut.isPending;
  const lastAssistant = [...messages].reverse().find((m) => m.role === "assistant");

  return (
    <Sheet open={open} onOpenChange={onOpenChange}>
      <SheetContent side="right" className="flex w-full max-w-md flex-col p-0 sm:max-w-md">
        <SheetHeader className="shrink-0 border-b px-4 py-3 text-left">
          <div className="flex items-center justify-between gap-2">
            <div className="flex items-center gap-2">
              <Sparkles className="size-5 text-primary" />
              <SheetTitle className="text-base">Ops copilot</SheetTitle>
            </div>
            <Button
              type="button"
              variant="ghost"
              size="icon"
              className="h-7 w-7"
              onClick={() => onOpenChange(false)}
              aria-label="Close"
            >
              <X className="size-4" />
            </Button>
          </div>
          <SheetDescription className="text-xs">
            Ask &quot;what needs me?&quot; — grounded in fleet, convoys and backlog. Links use [workspace/slug].
            {workspaceSlug ? ` · ${workspaceSlug}` : " · no workspace"}
          </SheetDescription>
        </SheetHeader>

        <div className="flex min-h-0 flex-1 flex-col">
          <div className="min-h-0 flex-1 overflow-y-auto px-3 py-3">
            {messages.length === 0 && !isBusy ? (
              <div className="space-y-3 px-1 py-6 text-center">
                <div className="mx-auto flex h-12 w-12 items-center justify-center rounded-xl bg-primary/10">
                  <Sparkles className="size-6 text-primary" />
                </div>
                <p className="text-sm font-medium">What needs you?</p>
                <p className="mx-auto max-w-[22rem] text-xs text-muted-foreground">
                  Try &quot;what needs my approval?&quot; — fleet → needs you will be cited with [fleet] links.
                </p>
                <div className="flex flex-wrap justify-center gap-2">
                  {["What needs me?", "What's ready to start?", "Show my gate inbox"].map((chip) => (
                    <button
                      key={chip}
                      type="button"
                      onClick={() => setInput(chip)}
                      className="rounded-full border bg-card px-3 py-1.5 text-xs hover:bg-muted"
                    >
                      {chip}
                    </button>
                  ))}
                </div>
                {!workspaceSlug && (
                  <p className="text-xs text-destructive">No workspace selected — create or select one first.</p>
                )}
              </div>
            ) : null}

            <div className="space-y-3">
              {messages.map((m) => (
                <div
                  key={m.id}
                  className={cn("flex gap-2", m.role === "user" ? "justify-end" : "justify-start")}
                >
                  <div
                    className={cn(
                      "max-w-[85%] rounded-lg px-3 py-2 text-sm whitespace-pre-wrap",
                      m.role === "user"
                        ? "bg-primary text-primary-foreground"
                        : "border bg-muted",
                    )}
                  >
                    {m.content}
                  </div>
                </div>
              ))}
              {isBusy && (
                <div className="flex gap-2">
                  <div className="rounded-lg border bg-card px-3 py-2">
                    <TypingDots />
                  </div>
                </div>
              )}
              {copilotMut.error && (
                <p className="rounded-md bg-destructive/10 px-3 py-2 text-xs text-destructive">
                  {copilotMut.error.message}
                </p>
              )}
              {copilotMut.data && (
                <p className="px-1 text-[10px] text-muted-foreground">
                  Model: {copilotMut.data.resolvedAlias} ({copilotMut.data.modelId})
                </p>
              )}
              <div ref={bottomRef} />
            </div>
          </div>

          <div className="shrink-0 border-t bg-muted/20 px-3 py-3">
            <div className="mb-2 flex items-center justify-between gap-2">
              <p className="text-[11px] text-muted-foreground">
                {lastAssistant ? "Need to create work from this answer?" : "Draft a Task from chat"}
              </p>
              <Button
                type="button"
                variant="outline"
                size="sm"
                className="h-7 text-xs"
                onClick={() => setDraftOpen((v) => !v)}
              >
                Draft Task
              </Button>
            </div>

            {draftOpen && (
              <div className="mb-3 rounded-md border bg-background p-3">
                <p className="mb-2 text-xs font-medium">Create backlog task via create-backlog-item shape</p>
                <div className="grid grid-cols-2 gap-2">
                  <div className="space-y-1">
                    <label className="text-[10px] font-medium uppercase text-muted-foreground">Plan slug</label>
                    <Input
                      value={draftPlanSlug}
                      onChange={(e) => setDraftPlanSlug(e.target.value)}
                      placeholder="automation-foundation"
                      className="h-8 text-xs"
                    />
                  </div>
                  <div className="space-y-1">
                    <label className="text-[10px] font-medium uppercase text-muted-foreground">Epic slug</label>
                    <Input
                      value={draftEpicSlug}
                      onChange={(e) => setDraftEpicSlug(e.target.value)}
                      placeholder="ops-copilot"
                      className="h-8 text-xs"
                    />
                  </div>
                  <div className="space-y-1">
                    <label className="text-[10px] font-medium uppercase text-muted-foreground">Task slug</label>
                    <Input
                      value={draftSlug}
                      onChange={(e) => setDraftSlug(e.target.value)}
                      placeholder="triage-bug"
                      className="h-8 text-xs"
                    />
                  </div>
                  <div className="space-y-1">
                    <label className="text-[10px] font-medium uppercase text-muted-foreground">Title</label>
                    <Input
                      value={draftTitle}
                      onChange={(e) => setDraftTitle(e.target.value)}
                      placeholder="Triage bug from copilot"
                      className="h-8 text-xs"
                    />
                  </div>
                </div>
                <div className="mt-2 space-y-1">
                  <label className="text-[10px] font-medium uppercase text-muted-foreground">Body markdown</label>
                  <textarea
                    value={draftBody}
                    onChange={(e) => setDraftBody(e.target.value)}
                    placeholder="One or two sentences. Will become Task-*.md"
                    rows={3}
                    className="w-full rounded-md border border-input bg-background px-2 py-1.5 text-xs"
                  />
                </div>
                <div className="mt-2 flex items-center justify-end gap-2">
                  <Button
                    type="button"
                    size="sm"
                    variant="ghost"
                    onClick={() => setDraftOpen(false)}
                    className="h-7 text-xs"
                  >
                    Cancel
                  </Button>
                  <Button
                    type="button"
                    size="sm"
                    className="h-7 text-xs"
                    disabled={
                      createTaskMut.isPending ||
                      !draftPlanSlug.trim() ||
                      !draftEpicSlug.trim() ||
                      !draftSlug.trim() ||
                      !draftTitle.trim() ||
                      !workspaceSlug
                    }
                    onClick={handleDraftTask}
                  >
                    {createTaskMut.isPending ? <Loader2 className="size-3 animate-spin" /> : "Create Task"}
                  </Button>
                </div>
                {createTaskMut.error && (
                  <p className="mt-2 text-xs text-destructive">{createTaskMut.error.message}</p>
                )}
                {createTaskMut.isSuccess && (
                  <p className="mt-2 text-xs text-green-600">Task created — check Plans tree.</p>
                )}
              </div>
            )}

            <div className="flex gap-2">
              <textarea
                value={input}
                onChange={(e) => setInput(e.target.value)}
                onKeyDown={onKeyDown}
                placeholder={workspaceSlug ? "What needs me?" : "Select workspace first"}
                disabled={isBusy || !workspaceSlug}
                rows={2}
                className={cn(
                  "min-h-[44px] flex-1 resize-none rounded-md border border-input bg-background px-3 py-2 text-sm",
                  "placeholder:text-muted-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring",
                )}
              />
              <Button
                type="button"
                size="icon"
                className="h-[44px] w-[44px] shrink-0"
                onClick={send}
                disabled={isBusy || !input.trim() || !workspaceSlug}
                aria-label="Send"
              >
                {isBusy ? <Loader2 className="size-4 animate-spin" /> : <Send className="size-4" />}
              </Button>
            </div>
          </div>
        </div>
      </SheetContent>
    </Sheet>
  );
}

export function OpsCopilotFab({ workspaceSlug }: { workspaceSlug: string }) {
  const [open, setOpen] = React.useState(false);
  return (
    <>
      <Button
        type="button"
        onClick={() => setOpen(true)}
        className="fixed bottom-6 right-6 z-40 h-12 w-12 rounded-full shadow-lg"
        size="icon"
        aria-label="Open ops copilot"
      >
        <Sparkles className="size-5" />
      </Button>
      <OpsCopilotPanel workspaceSlug={workspaceSlug} open={open} onOpenChange={setOpen} />
    </>
  );
}