"use client";

import { useEffect, useMemo, useRef, useState } from "react";
import { AnimatePresence, motion } from "framer-motion";
import { Bot, Check, Copy, Loader2, Play, Square, X } from "lucide-react";
import { Button } from "@/components/ui/Button";
import { Input } from "@/components/ui/Input";
import { Select } from "@/components/ui/Select";
import { Textarea } from "@/components/ui/Textarea";
import {
  fetchModelStreamModels,
  streamModelGeneration,
  type ModelStreamEvent,
  type ModelStreamModelsResponse,
  type ModelStreamRequest
} from "@/lib/api";
import { cn } from "@/lib/utils";

interface ModelStreamPanelProps {
  open: boolean;
  onClose: () => void;
  onStreamStart: () => void;
  onStreamRawText: (rawText: string, done: boolean) => void;
  onStreamError: (message: string) => void;
}

const defaultPrompt =
  "If a store sells 3 notebooks for $12, how much would 8 notebooks cost at the same rate?";
const infiniteTokenCap = 32768;

function numberValue(value: string, fallback: number) {
  const next = Number(value);
  return Number.isFinite(next) ? next : fallback;
}

function boundedIntegerValue(value: string, fallback: number, min: number, max: number) {
  return Math.min(max, Math.max(min, Math.round(numberValue(value, fallback))));
}

function numericDiagnostic(value: unknown) {
  return typeof value === "number" && Number.isFinite(value) ? value : null;
}

function diagnosticValue(value: unknown) {
  if (value == null || value === "") return "";
  if (Array.isArray(value)) return value.map(String).join(", ");
  if (typeof value === "object") {
    const entries = Object.entries(value as Record<string, unknown>);
    if (entries.length === 0) return "none";
    return entries.map(([key, count]) => `${key}:${String(count)}`).join(", ");
  }
  if (typeof value === "number") return Number.isInteger(value) ? value.toLocaleString() : value.toFixed(2);
  return String(value);
}

function generationDiagnosticItems(data: Record<string, unknown> | null) {
  if (!data) return [];
  const tokensPerSecond = numericDiagnostic(data.tokensPerSecond);
  const generatedTokens = numericDiagnostic(data.generatedTokens);
  const adapterState =
    data.adapterMerged === true
      ? "merged"
      : data.adapterPath
        ? data.adapterMergeError === "quantized_adapter_wrapper"
          ? "wrapped"
          : "loaded"
        : "base";
  const items = [
    ["Device", diagnosticValue(data.device ?? data.parameterDevices)],
    ["Dtype", diagnosticValue(data.dtype ?? data.precision)],
    ["Attention", diagnosticValue(data.attention)],
    ["Prompt", data.promptTokens ? `${diagnosticValue(data.promptTokens)} tok` : ""],
    ["LoRA", adapterState],
    ["Offload", diagnosticValue(data.offloaded)]
  ];
  if (generatedTokens != null) items.push(["Output", `${generatedTokens.toLocaleString()} tok`]);
  if (tokensPerSecond != null) items.push(["Speed", `${tokensPerSecond.toFixed(1)} tok/s`]);
  return items.filter(([, value]) => value);
}

export function ModelStreamPanel({
  open,
  onClose,
  onStreamStart,
  onStreamRawText,
  onStreamError
}: ModelStreamPanelProps) {
  const [prompt, setPrompt] = useState(defaultPrompt);
  const [modelCatalog, setModelCatalog] = useState<ModelStreamModelsResponse | null>(null);
  const [modelId, setModelId] = useState("Qwen/Qwen2.5-1.5B-Instruct");
  const [adapterPath, setAdapterPath] = useState("");
  const [systemPrompt, setSystemPrompt] = useState("");
  const [systemPromptOpen, setSystemPromptOpen] = useState(false);
  const [precision, setPrecision] = useState<ModelStreamRequest["precision"]>("bf16");
  const [tokenMode, setTokenMode] = useState<"limited" | "infinite">("limited");
  const [maxNewTokens, setMaxNewTokens] = useState("2048");
  const [temperature, setTemperature] = useState("0.7");
  const [topP, setTopP] = useState("0.9");
  const [topK, setTopK] = useState("50");
  const [repetitionPenalty, setRepetitionPenalty] = useState("1.05");
  const [doSample, setDoSample] = useState(true);
  const [rawGeneration, setRawGeneration] = useState("");
  const [status, setStatus] = useState("idle");
  const [error, setError] = useState("");
  const [stage, setStage] = useState<"configure" | "streaming" | "done">("configure");
  const [isStreaming, setIsStreaming] = useState(false);
  const [copiedRaw, setCopiedRaw] = useState(false);
  const [diagnostics, setDiagnostics] = useState<Record<string, unknown> | null>(null);
  const abortRef = useRef<AbortController | null>(null);
  const rawRef = useRef("");
  const parsedLengthRef = useRef(0);

  const modelChoices = useMemo(() => modelCatalog?.models ?? [], [modelCatalog]);
  const selectedModel = useMemo(
    () => modelChoices.find((choice) => choice.modelId === modelId || choice.id === modelId) ?? null,
    [modelChoices, modelId]
  );
  const checkpointOptions = selectedModel?.checkpoints ?? [];
  const diagnosticItems = useMemo(() => generationDiagnosticItems(diagnostics), [diagnostics]);

  useEffect(() => {
    if (!open || modelCatalog) return;
    let cancelled = false;
    setError("");
    fetchModelStreamModels()
      .then((catalog) => {
        if (cancelled) return;
        const defaultModel =
          catalog.models.find((choice) => choice.modelId === catalog.defaultModelId) ?? catalog.models[0];
        setModelCatalog(catalog);
        setModelId(defaultModel?.modelId ?? catalog.defaultModelId);
        setAdapterPath(defaultModel?.defaultCheckpointPath ?? catalog.defaultAdapterPath ?? "");
        setSystemPrompt(defaultModel?.systemPrompt ?? "");
      })
      .catch((nextError) => {
        if (!cancelled) setError(nextError instanceof Error ? nextError.message : String(nextError));
      });
    return () => {
      cancelled = true;
    };
  }, [modelCatalog, open]);

  const handleModelChange = (nextModelId: string) => {
    setModelId(nextModelId);
    const nextModel = modelChoices.find((choice) => choice.modelId === nextModelId || choice.id === nextModelId);
    setAdapterPath(nextModel?.defaultCheckpointPath ?? "");
    setSystemPrompt(nextModel?.systemPrompt ?? "");
  };

  const handleEvent = (streamEvent: ModelStreamEvent) => {
    if (streamEvent.event === "status") {
      setStatus(String(streamEvent.data.message ?? "streaming"));
      setDiagnostics(streamEvent.data);
      return;
    }

    if (streamEvent.event === "token") {
      const text = typeof streamEvent.data.text === "string" ? streamEvent.data.text : "";
      rawRef.current += text;
      setRawGeneration(rawRef.current);
      const completedIndex = Math.max(
        rawRef.current.lastIndexOf("</trajectory>"),
        rawRef.current.lastIndexOf("</|trajectory|>"),
        rawRef.current.lastIndexOf("</|end_of_trajectory|>"),
        rawRef.current.lastIndexOf("<|end_of_trajectory|>")
      );
      if (completedIndex > parsedLengthRef.current) {
        parsedLengthRef.current = completedIndex;
        onStreamRawText(rawRef.current, false);
      }
      return;
    }

    if (streamEvent.event === "trajectory" || streamEvent.event === "trajectory_update") {
      parsedLengthRef.current = rawRef.current.length;
      onStreamRawText(rawRef.current, false);
      return;
    }

    if (streamEvent.event === "done") {
      const rawText = typeof streamEvent.data.rawText === "string" ? streamEvent.data.rawText : rawRef.current;
      rawRef.current = rawText;
      setRawGeneration(rawText);
      onStreamRawText(rawText, true);
      setStatus("done");
      setDiagnostics((current) => ({ ...(current ?? {}), ...streamEvent.data, message: "done" }));
      setStage("done");
      setIsStreaming(false);
      return;
    }

    if (streamEvent.event === "error") {
      const message = String(streamEvent.data.error ?? "Model stream failed.");
      setError(message);
      onStreamError(message);
      setStatus("error");
      setStage("done");
      setIsStreaming(false);
    }
  };

  const startStream = async () => {
    if (!prompt.trim() || !modelId || isStreaming) return;
    const controller = new AbortController();
    abortRef.current = controller;
    rawRef.current = "";
    parsedLengthRef.current = 0;
    setRawGeneration("");
    setCopiedRaw(false);
    setDiagnostics(null);
    setError("");
    setStatus("starting");
    setStage("streaming");
    setIsStreaming(true);
    onStreamStart();
    const defaultSystemPrompt = selectedModel?.systemPrompt?.trim() ?? "";
    const nextSystemPrompt = systemPrompt.trim();
    const systemPromptOverride =
      nextSystemPrompt && nextSystemPrompt !== defaultSystemPrompt ? nextSystemPrompt : null;

    try {
      await streamModelGeneration(
        {
          prompt,
          system_prompt: systemPromptOverride,
          model_id: modelId,
          adapter_path: adapterPath.trim() || null,
          precision,
          max_new_tokens:
            tokenMode === "limited"
              ? boundedIntegerValue(maxNewTokens, 2048, 1, infiniteTokenCap)
              : null,
          temperature: numberValue(temperature, 0.7),
          top_p: numberValue(topP, 0.9),
          top_k: boundedIntegerValue(topK, 50, 0, 1000),
          repetition_penalty: numberValue(repetitionPenalty, 1.05),
          do_sample: doSample
        },
        handleEvent,
        controller.signal
      );
      if (!controller.signal.aborted) {
        setStatus("done");
        setStage("done");
      }
    } catch (nextError) {
      if (controller.signal.aborted) {
        setStatus("stopped");
      } else {
        const message = nextError instanceof Error ? nextError.message : String(nextError);
        setError(message);
        onStreamError(message);
        setStatus("error");
      }
      setStage("done");
    } finally {
      setIsStreaming(false);
      abortRef.current = null;
    }
  };

  const stopStream = () => {
    abortRef.current?.abort();
    setIsStreaming(false);
    setStatus("stopped");
    setStage("done");
  };

  const copyRawGeneration = async () => {
    if (!rawGeneration) return;
    try {
      await navigator.clipboard.writeText(rawGeneration);
      setCopiedRaw(true);
      window.setTimeout(() => setCopiedRaw(false), 1400);
    } catch (nextError) {
      const message = nextError instanceof Error ? nextError.message : String(nextError);
      setError(`Copy failed: ${message}`);
    }
  };

  const handleClose = () => {
    if (!isStreaming) setStage("configure");
    onClose();
  };

  const openNewRun = () => {
    if (isStreaming) return;
    setError("");
    setStatus("idle");
    setRawGeneration("");
    setCopiedRaw(false);
    setDiagnostics(null);
    rawRef.current = "";
    parsedLengthRef.current = 0;
    setStage("configure");
  };

  const renderConfigureModal = () => (
    <motion.div
      initial={{ opacity: 0 }}
      animate={{ opacity: 1 }}
      exit={{ opacity: 0 }}
      transition={{ duration: 0.16 }}
      className="fixed inset-0 z-50 flex items-center justify-center bg-ink-900/30 p-4 backdrop-blur-[2px]"
    >
      <motion.section
        initial={{ opacity: 0, scale: 0.97, y: 14 }}
        animate={{ opacity: 1, scale: 1, y: 0 }}
        exit={{ opacity: 0, scale: 0.98, y: 10 }}
        transition={{ duration: 0.18 }}
        className="flex max-h-[calc(100vh-2rem)] w-[min(780px,calc(100vw-2rem))] flex-col overflow-hidden rounded-xl border border-paper-300 bg-white shadow-soft"
      >
        <div className="flex items-center justify-between border-b border-paper-300 px-5 py-4">
          <div className="flex min-w-0 items-center gap-3">
            <span className="flex h-10 w-10 shrink-0 items-center justify-center rounded-lg bg-claude-50 text-claude-700">
              <Bot className="h-5 w-5" />
            </span>
            <div className="min-w-0">
              <h2 className="truncate text-base font-semibold text-ink-900">Create tree by model</h2>
              <p className="truncate text-xs text-ink-500">{status}</p>
            </div>
          </div>
          <Button size="icon" variant="ghost" onClick={handleClose} title="Close">
            <X className="h-4 w-4" />
          </Button>
        </div>

        <div className="scrollbar-thin flex-1 space-y-5 overflow-auto p-5">
          <label className="block text-xs font-semibold uppercase text-ink-500">
            Question prompt
            <Textarea
              className="mt-2 min-h-32 resize-y"
              value={prompt}
              onChange={(event) => setPrompt(event.target.value)}
              disabled={isStreaming}
            />
          </label>

          <details
            open={systemPromptOpen}
            onToggle={(event) => setSystemPromptOpen(event.currentTarget.open)}
            className="rounded-lg border border-paper-300 bg-paper-50/70"
          >
            <summary className="flex cursor-pointer select-none items-center justify-between gap-3 px-3 py-2 text-xs font-semibold uppercase text-ink-600">
              <span>System prompt</span>
              <span className="truncate text-[11px] font-medium normal-case text-ink-400">
                {selectedModel?.settingsPath ?? "Loaded from wrapper model_settings.yaml"}
              </span>
            </summary>
            <div className="space-y-2 border-t border-paper-300 p-3">
              <Textarea
                className="min-h-44 resize-y font-mono text-xs leading-5"
                value={systemPrompt}
                onChange={(event) => setSystemPrompt(event.target.value)}
                disabled={isStreaming}
                placeholder="Wrapper system prompt"
              />
              <div className="flex items-center justify-between gap-3 text-xs text-ink-500">
                <span>
                  {systemPrompt.trim() === (selectedModel?.systemPrompt?.trim() ?? "")
                    ? "Using wrapper prompt"
                    : "Using edited prompt for this run"}
                </span>
                <Button
                  size="sm"
                  variant="ghost"
                  onClick={() => setSystemPrompt(selectedModel?.systemPrompt ?? "")}
                  disabled={isStreaming}
                >
                  Reset
                </Button>
              </div>
            </div>
          </details>

          <div className="grid grid-cols-1 gap-3 md:grid-cols-2">
            <label className="text-xs font-semibold uppercase text-ink-500">
              Model
              <Select
                className="mt-2"
                value={modelId}
                onChange={(event) => handleModelChange(event.target.value)}
                disabled={isStreaming || modelChoices.length === 0}
              >
                {modelChoices.length === 0 ? (
                  <option value={modelId}>{modelId}</option>
                ) : (
                  modelChoices.map((choice) => (
                    <option key={choice.key} value={choice.modelId}>
                      {choice.label}
                    </option>
                  ))
                )}
              </Select>
            </label>

            <label className="text-xs font-semibold uppercase text-ink-500">
              Checkpoint
              <Select
                className="mt-2"
                value={adapterPath}
                onChange={(event) => setAdapterPath(event.target.value)}
                disabled={isStreaming}
              >
                <option value="">Base model</option>
                {checkpointOptions.map((checkpoint) => (
                  <option key={checkpoint.path} value={checkpoint.path}>
                    {checkpoint.label}
                  </option>
                ))}
                {adapterPath && !checkpointOptions.some((checkpoint) => checkpoint.path === adapterPath) && (
                  <option value={adapterPath}>{adapterPath}</option>
                )}
              </Select>
            </label>
          </div>

          <label className="block text-xs font-semibold uppercase text-ink-500">
            Custom checkpoint path
            <Input
              className="mt-2 font-mono text-xs"
              value={adapterPath}
              onChange={(event) => setAdapterPath(event.target.value)}
              disabled={isStreaming}
              placeholder="Optional LoRA adapter directory"
            />
          </label>

          <div className="grid grid-cols-1 gap-4 md:grid-cols-[1fr_220px]">
            <label className="text-xs font-semibold uppercase text-ink-500">
              Temperature
              <div className="mt-2 flex items-center gap-3">
                <input
                  type="range"
                  min="0"
                  max="2"
                  step="0.05"
                  value={temperature}
                  onChange={(event) => setTemperature(event.target.value)}
                  disabled={isStreaming}
                  className="h-2 w-full accent-claude-500"
                />
                <Input
                  className="w-20"
                  inputMode="decimal"
                  value={temperature}
                  onChange={(event) => setTemperature(event.target.value)}
                  disabled={isStreaming}
                />
              </div>
            </label>

            <label className="text-xs font-semibold uppercase text-ink-500">
              Precision
              <Select
                className="mt-2"
                value={precision}
                onChange={(event) => setPrecision(event.target.value as ModelStreamRequest["precision"])}
                disabled={isStreaming}
              >
                <option value="bf16">bf16</option>
                <option value="fp16">fp16</option>
                <option value="fp32">fp32</option>
                <option value="4bit">4bit</option>
                <option value="8bit">8bit</option>
              </Select>
            </label>
          </div>

          <div className="grid grid-cols-1 gap-3 md:grid-cols-[220px_1fr]">
            <div className="text-xs font-semibold uppercase text-ink-500">
              Token limit
              <div className="mt-2 inline-flex h-9 rounded-lg border border-paper-300 bg-paper-50 p-1">
                {(["limited", "infinite"] as const).map((mode) => (
                  <button
                    key={mode}
                    type="button"
                    onClick={() => setTokenMode(mode)}
                    disabled={isStreaming}
                    className={cn(
                      "h-7 rounded-md px-3 text-xs font-semibold capitalize transition",
                      tokenMode === mode ? "bg-white text-claude-700 shadow-sm" : "text-ink-500 hover:text-ink-900"
                    )}
                  >
                    {mode}
                  </button>
                ))}
              </div>
            </div>

            <label className="text-xs font-semibold uppercase text-ink-500">
              Max new tokens
              <Input
                className="mt-2"
                inputMode="numeric"
                value={tokenMode === "infinite" ? "Until EOS (32k cap)" : maxNewTokens}
                onChange={(event) => setMaxNewTokens(event.target.value)}
                disabled={isStreaming || tokenMode === "infinite"}
              />
            </label>
          </div>

          <div className="grid grid-cols-2 gap-3 md:grid-cols-4">
            <label className="text-xs font-semibold uppercase text-ink-500">
              Top P
              <Input className="mt-2" value={topP} onChange={(event) => setTopP(event.target.value)} disabled={isStreaming} />
            </label>
            <label className="text-xs font-semibold uppercase text-ink-500">
              Top K
              <Input className="mt-2" value={topK} onChange={(event) => setTopK(event.target.value)} disabled={isStreaming} />
            </label>
            <label className="text-xs font-semibold uppercase text-ink-500">
              Repeat
              <Input
                className="mt-2"
                value={repetitionPenalty}
                onChange={(event) => setRepetitionPenalty(event.target.value)}
                disabled={isStreaming}
              />
            </label>
            <label className="flex items-end gap-2 pb-2 text-xs font-semibold uppercase text-ink-500">
              <input
                type="checkbox"
                checked={doSample}
                onChange={(event) => setDoSample(event.target.checked)}
                disabled={isStreaming}
                className="h-4 w-4 rounded border-paper-300 text-claude-600"
              />
              Sampling
            </label>
          </div>

          {error && (
            <div className="rounded-lg border border-red-200 bg-red-50 px-3 py-2 text-sm text-red-700">
              {error}
            </div>
          )}
        </div>

        <div className="flex items-center justify-between gap-3 border-t border-paper-300 px-5 py-4">
          <div className="truncate text-xs text-ink-500">
            {selectedModel ? selectedModel.wrapperDir : "Loading model choices"}
          </div>
          <Button variant="primary" onClick={startStream} disabled={!prompt.trim() || !modelId || isStreaming}>
            {isStreaming ? <Loader2 className="h-4 w-4 animate-spin" /> : <Play className="h-4 w-4" />}
            Generate tree
          </Button>
        </div>
      </motion.section>
    </motion.div>
  );

  const renderMonitor = () => (
    <motion.aside
      initial={{ opacity: 0, y: 14 }}
      animate={{ opacity: 1, y: 0 }}
      exit={{ opacity: 0, y: 14 }}
      transition={{ duration: 0.18 }}
      className="absolute bottom-5 left-5 z-30 flex max-h-[min(430px,calc(100vh-7rem))] w-[min(560px,calc(100vw-2rem))] flex-col overflow-hidden rounded-xl border border-paper-300 bg-white/94 shadow-soft backdrop-blur-xl"
    >
      <div className="flex items-center justify-between border-b border-paper-300 px-4 py-3">
        <div className="flex min-w-0 items-center gap-2">
          <Bot className="h-4 w-4 shrink-0 text-claude-600" />
          <div className="min-w-0">
            <h2 className="truncate text-sm font-semibold text-ink-900">Model generation</h2>
            <p className="truncate text-xs text-ink-500">{status}</p>
          </div>
        </div>
        <div className="flex items-center gap-2">
          {isStreaming ? (
            <Button size="sm" variant="danger" onClick={stopStream}>
              <Square className="h-4 w-4" />
              Stop
            </Button>
          ) : (
            <Button size="sm" onClick={openNewRun}>
              <Play className="h-4 w-4" />
              New run
            </Button>
          )}
          <Button
            size="sm"
            variant="ghost"
            onClick={() => void copyRawGeneration()}
            disabled={!rawGeneration}
            title="Copy raw generation"
          >
            {copiedRaw ? <Check className="h-4 w-4" /> : <Copy className="h-4 w-4" />}
            {copiedRaw ? "Copied" : "Copy raw"}
          </Button>
          <Button size="icon" variant="ghost" onClick={handleClose} title="Hide raw generation">
            <X className="h-4 w-4" />
          </Button>
        </div>
      </div>

      <div className="flex-1 space-y-3 overflow-hidden p-4">
        {diagnosticItems.length > 0 && (
          <div className="grid grid-cols-2 gap-2 md:grid-cols-4">
            {diagnosticItems.map(([label, value]) => (
              <div key={label} className="min-w-0 rounded-md border border-paper-300 bg-paper-50 px-2 py-1.5">
                <div className="text-[10px] font-semibold uppercase text-ink-400">{label}</div>
                <div className="truncate text-xs font-medium text-ink-800" title={value}>
                  {value}
                </div>
              </div>
            ))}
          </div>
        )}
        <Textarea
          className="h-72 min-h-0 resize-none font-mono text-xs leading-5"
          value={rawGeneration}
          readOnly
          placeholder="Streaming output"
        />
        {error && (
          <div className="rounded-lg border border-red-200 bg-red-50 px-3 py-2 text-sm text-red-700">
            {error}
          </div>
        )}
      </div>

      <div className="flex items-center justify-between border-t border-paper-300 px-4 py-2 text-xs text-ink-500">
        <span className="truncate">{modelId}</span>
        <span>{rawGeneration.length.toLocaleString()} chars</span>
      </div>
    </motion.aside>
  );

  return (
    <AnimatePresence>
      {open && (stage === "configure" ? renderConfigureModal() : renderMonitor())}
    </AnimatePresence>
  );
}