"use client";

import {
  useEffect,
  useRef,
  useState,
  type Dispatch,
  type SetStateAction,
} from "react";
import type {
  ChatMessage,
  ConnectionStatus,
  WorkPackage,
} from "@/lib/work-package-types";
import type { LlmConfig } from "@/lib/llm-config";
import { Button } from "@/components/ui/button";
import { Input } from "@/components/ui/input";
import { Textarea } from "@/components/ui/textarea";
import { ScrollArea } from "@/components/ui/scroll-area";
import {
  applyComposerSuggestion,
  getComposerSuggestions,
  type ComposerSuggestion,
} from "@/lib/composer-autocomplete";
import {
  AlertCircle,
  CheckCircle2,
  LoaderCircle,
  Send,
  Settings2,
  Sparkles,
  X,
} from "lucide-react";

function statusTone(status: ConnectionStatus) {
  if (status === "connected") return "text-emerald-700";
  if (status === "checking") return "text-amber-700";
  if (status === "error") return "text-rose-700";
  return "text-muted-foreground";
}

function StatusIcon(props: { status: ConnectionStatus }) {
  const { status } = props;
  if (status === "connected") return <CheckCircle2 className="h-3.5 w-3.5" />;
  if (status === "checking") {
    return <LoaderCircle className="h-3.5 w-3.5 animate-spin" />;
  }
  if (status === "error") return <AlertCircle className="h-3.5 w-3.5" />;
  return <Settings2 className="h-3.5 w-3.5" />;
}

export function ChatPanel(props: {
  messages: ChatMessage[];
  draft: string;
  setDraft: (v: string) => void;
  busy: boolean;
  productTitle: string;
  currentActivity: string;
  workPackages: WorkPackage[];
  selectedWorkPackageId?: string;
  onSelectWorkPackage: (id: string) => void;
  llmConfig: LlmConfig;
  setLlmConfig: Dispatch<SetStateAction<LlmConfig>>;
  isMockMode: boolean;
  connectionStatus: ConnectionStatus;
  connectionMessage: string;
  canTestConnection: boolean;
  onTestConnection: () => void;
  onSend: (text: string) => void | Promise<void>;
  initialSettingsOpen?: boolean;
}) {
  const {
    messages,
    draft,
    setDraft,
    busy,
    productTitle,
    currentActivity,
    workPackages,
    selectedWorkPackageId,
    onSelectWorkPackage,
    llmConfig,
    setLlmConfig,
    isMockMode,
    connectionStatus,
    connectionMessage,
    canTestConnection,
    onTestConnection,
    onSend,
    initialSettingsOpen,
  } = props;
  const bottomRef = useRef<HTMLDivElement | null>(null);
  const [settingsOpen, setSettingsOpen] = useState(initialSettingsOpen ?? false);
  const [activeSuggestionIndex, setActiveSuggestionIndex] = useState(0);
  const showSettings = settingsOpen;
  const selectedWorkPackage = workPackages.find(
    (workPackage) => workPackage.id === selectedWorkPackageId,
  );
  const suggestions = getComposerSuggestions(draft, workPackages);

  useEffect(() => {
    bottomRef.current?.scrollIntoView({ block: "end" });
  }, [messages.length]);

  function applySuggestion(suggestion: ComposerSuggestion) {
    setDraft(
      applyComposerSuggestion({
        draft,
        suggestion,
        selectedWorkPackage,
      }),
    );
    setActiveSuggestionIndex(0);

    if (suggestion.kind === "package") {
      onSelectWorkPackage(suggestion.id);
    }
  }

  return (
    <div className="flex h-full min-h-0 flex-col bg-muted/18">
      <div className="px-4 py-3 md:px-5">
        <div className="text-sm font-semibold">{productTitle}</div>
        <div className="text-xs text-muted-foreground">
          Use <span className="font-mono">@SRS ask</span>,{" "}
          <span className="font-mono">@Design FMEA execute</span>,{" "}
          <span className="font-mono">/plan</span>, or paste a product idea to
          auto-run the whole board.
        </div>
      </div>

      <div className="px-4 pb-2 md:px-5">
        <div className="rounded-2xl bg-background/82 px-3 py-2 shadow-sm ring-1 ring-black/5">
          <div className="flex items-center gap-2 text-[11px] font-medium">
            <Sparkles className="h-3.5 w-3.5 text-primary" />
            <span>{busy ? currentActivity : "Ready. You can describe a product or target a package directly."}</span>
          </div>
          <div className="mt-1 text-[11px] leading-5 text-muted-foreground">
            Tip: type <span className="font-mono">@</span> for packages or{" "}
            <span className="font-mono">/</span> for ask, plan, change, and
            execute shortcuts.
          </div>
        </div>
      </div>

      <ScrollArea className="min-h-0 flex-1">
        <div className="space-y-3 px-4 py-1 md:px-5">
          {messages.map((message) => (
            <div
              key={message.id}
              className={[
                "max-w-[52rem] whitespace-pre-wrap rounded-xl px-3 py-2 text-sm leading-6 shadow-sm ring-1 ring-black/5",
                message.role === "user"
                  ? "ml-auto bg-secondary/90"
                  : "mr-auto bg-background",
              ].join(" ")}
            >
              <div className="mb-1 text-[11px] font-medium text-muted-foreground">
                {message.role === "user" ? "You" : productTitle}
              </div>
              <div>{message.content}</div>
            </div>
          ))}
          <div ref={bottomRef} />
        </div>
      </ScrollArea>

      <div className="relative p-4 pt-3 md:p-5 md:pt-3">
        {suggestions.length ? (
          <div className="absolute inset-x-4 bottom-[calc(100%+0.75rem)] z-20 rounded-2xl bg-background/96 p-2 shadow-lg ring-1 ring-black/10 md:inset-x-5">
            <div className="space-y-1">
              {suggestions.map((suggestion, index) => {
                const active = index === activeSuggestionIndex;

                return (
                  <button
                    key={
                      suggestion.kind === "package"
                        ? suggestion.id
                        : suggestion.mode
                    }
                    type="button"
                    className={[
                      "flex w-full items-start justify-between gap-3 rounded-xl px-3 py-2 text-left transition-colors",
                      active ? "bg-muted" : "hover:bg-muted/70",
                    ].join(" ")}
                    onClick={() => applySuggestion(suggestion)}
                  >
                    <div className="min-w-0">
                      <div className="text-sm font-medium">
                        {suggestion.kind === "package"
                          ? `@${suggestion.shortName}`
                          : suggestion.label}
                      </div>
                      <div className="text-xs text-muted-foreground">
                        {suggestion.kind === "package"
                          ? suggestion.title
                          : suggestion.description}
                      </div>
                    </div>
                    <div className="pt-0.5 text-[11px] text-muted-foreground">
                      {suggestion.kind === "package" ? "Package" : "Action"}
                    </div>
                  </button>
                );
              })}
            </div>
          </div>
        ) : null}

        {showSettings ? (
          <div className="absolute inset-x-4 bottom-[calc(100%+0.75rem)] z-20 rounded-2xl bg-background px-3 py-3 shadow-lg ring-1 ring-black/10 md:inset-x-5">
            <div className="flex items-start justify-between gap-3">
              <div>
                <div className="text-xs font-semibold">Model Settings</div>
                <div className="text-[11px] text-muted-foreground">
                  Stored locally in this browser. Live mode turns on after the connection test succeeds.
                </div>
              </div>
              <Button
                variant="ghost"
                size="icon"
                className="h-7 w-7 rounded-xl"
                onClick={() => setSettingsOpen(false)}
              >
                <X className="h-4 w-4" />
              </Button>
            </div>

            <div
              className={[
                "mt-3 flex items-center gap-2 rounded-xl bg-muted/28 px-2.5 py-2 text-[11px]",
                statusTone(connectionStatus),
              ].join(" ")}
            >
              <StatusIcon status={connectionStatus} />
              <span>{connectionMessage}</span>
            </div>

            <div className="mt-3 space-y-2.5">
              <div>
                <div className="mb-1 text-[11px] font-medium text-muted-foreground">
                  API Key
                </div>
                <Input
                  type="password"
                  value={llmConfig.apiKey}
                  placeholder="Paste your API key"
                  className="h-9 rounded-xl bg-background/92"
                  onChange={(e) =>
                    setLlmConfig((prev) => ({
                      ...prev,
                      apiKey: e.target.value,
                    }))
                  }
                />
              </div>

              <div className="grid gap-2 md:grid-cols-2">
                <div>
                  <div className="mb-1 text-[11px] font-medium text-muted-foreground">
                    Base URL
                  </div>
                  <Input
                    value={llmConfig.baseUrl}
                    className="h-9 rounded-xl bg-background/92"
                    onChange={(e) =>
                      setLlmConfig((prev) => ({
                        ...prev,
                        baseUrl: e.target.value,
                      }))
                    }
                  />
                </div>
                <div>
                  <div className="mb-1 text-[11px] font-medium text-muted-foreground">
                    Model
                  </div>
                  <Input
                    value={llmConfig.model}
                    className="h-9 rounded-xl bg-background/92"
                    onChange={(e) =>
                      setLlmConfig((prev) => ({
                        ...prev,
                        model: e.target.value,
                      }))
                    }
                  />
                </div>
              </div>

              <div className="flex justify-end">
                <Button
                  type="button"
                  variant="outline"
                  className="h-8 rounded-xl px-3 text-[11px]"
                  disabled={!canTestConnection || connectionStatus === "checking"}
                  onClick={onTestConnection}
                >
                  <StatusIcon status={connectionStatus} />
                  <span className="ml-1">
                    {connectionStatus === "checking"
                      ? "Testing connection..."
                      : "Test connection"}
                  </span>
                </Button>
              </div>
            </div>
          </div>
        ) : null}

        <form
          className="flex items-end gap-2.5"
          onSubmit={(event) => {
            event.preventDefault();
            onSend(draft);
          }}
        >
          <Textarea
            value={draft}
            onChange={(event) => {
              setDraft(event.target.value);
              setActiveSuggestionIndex(0);
            }}
            placeholder="Type a product idea, @Package..., or /ask /plan /change /execute ..."
            className="min-h-[148px] resize-none rounded-[24px] bg-background/96 px-4 py-3.5 text-sm leading-6 shadow-sm ring-1 ring-black/5"
            onKeyDown={(event) => {
              if (suggestions.length && event.key === "ArrowDown") {
                event.preventDefault();
                setActiveSuggestionIndex((current) =>
                  Math.min(current + 1, suggestions.length - 1),
                );
                return;
              }

              if (suggestions.length && event.key === "ArrowUp") {
                event.preventDefault();
                setActiveSuggestionIndex((current) => Math.max(current - 1, 0));
                return;
              }

              if (suggestions.length && event.key === "Escape") {
                event.preventDefault();
                setDraft(draft.replace(/(?:^|\s)([@/][A-Za-z\s-]*)$/, ""));
                return;
              }

              if (
                suggestions.length &&
                event.key === "Enter" &&
                !event.metaKey &&
                !event.ctrlKey
              ) {
                event.preventDefault();
                applySuggestion(suggestions[activeSuggestionIndex] ?? suggestions[0]);
                return;
              }

              if (event.key === "Enter" && (event.metaKey || event.ctrlKey)) {
                event.preventDefault();
                onSend(draft);
              }
            }}
          />
          <Button
            type="submit"
            disabled={busy || !draft.trim()}
            size="icon"
            className="h-12 w-12 rounded-2xl"
          >
            <Send className="h-4 w-4" />
          </Button>
        </form>

        <div className="mt-2 flex items-center justify-between gap-3">
          <div className="text-xs text-muted-foreground">
            Press <span className="font-mono">Ctrl</span>+
            <span className="font-mono">Enter</span> to send. Use{" "}
            <span className="font-mono">@</span> or{" "}
            <span className="font-mono">/</span> for suggestions.
          </div>
          <Button
            type="button"
            variant="ghost"
            className="h-8 rounded-xl px-2.5 text-[11px]"
            onClick={() => setSettingsOpen((value) => !value)}
          >
            <StatusIcon status={connectionStatus} />
            <span className="ml-1">
              {isMockMode ? "Model Settings" : "Live Settings"}
            </span>
          </Button>
        </div>
      </div>
    </div>
  );
}