import { useState, useEffect, useRef } from "react";
import Editor from "@monaco-editor/react";
import { askAgent } from "./agent/assistant";
import { runCode } from "./agent/runner";
import {
  loadTree,
  saveTree,
  addFile,
  addFolder,
  renameNode,
  deleteNode,
  getNodeByPath,
  updateFileContent,
  searchTree,
} from "./fileStore";
import { downloadProjectZip } from "./zipExport";
import { parseProblems } from "./problemParser";
import "./App.css";

// =================== SUPPORTED LANGUAGES ===================
const LANGUAGE_OPTIONS = [
  { id: "python", ext: ".py", icon: "🐍", monaco: "python" },
  { id: "javascript", ext: ".js", icon: "🟨", monaco: "javascript" },
  { id: "typescript", ext: ".ts", icon: "🟦", monaco: "typescript" },
  { id: "cpp", ext: ".cpp", icon: "💠", monaco: "cpp" },
  { id: "c", ext: ".c", icon: "🔷", monaco: "c" },
  { id: "java", ext: ".java", icon: "☕", monaco: "java" },
  { id: "html", ext: ".html", icon: "🌐", monaco: "html" },
  { id: "css", ext: ".css", icon: "🎨", monaco: "css" },
  { id: "json", ext: ".json", icon: "🧾", monaco: "json" },
];

const RUNNABLE_LANGS = ["python", "javascript", "java"];

// Utility: detect whether output likely requests input
function outputLooksForInput(output) {
  if (!output) return false;
  const o = output.toString();
  // common prompt words / patterns and trailing prompt char
  const patterns = [
    /enter.*:/i,
    /input.*:/i,
    /please enter/i,
    /scanner/i, // java Scanner exceptions or prompts
    /press enter/i,
    /: $/, // ends with colon + space (e.g. "Enter number: ")
    /:\n$/, // ends with colon + newline
    /> $/, // trailing >
  ];
  return patterns.some((p) => p.test(o));
}

// =================== APP ===================
function App() {
  const [tree, setTree] = useState(loadTree());
  const [activePath, setActivePath] = useState("main.py"); // selected file or folder path
  // Terminal-ish state
  const [terminalLines, setTerminalLines] = useState([]); // array of strings shown in terminal
  const [terminalInput, setTerminalInput] = useState(""); // current typed input in terminal prompt
  const [accumStdin, setAccumStdin] = useState(""); // accumulated stdin passed to backend
  const [awaitingInput, setAwaitingInput] = useState(false); // true if program waiting for input
  const [output, setOutput] = useState(""); // last raw output (kept for compatibility)
  const [prompt, setPrompt] = useState("");
  const [explanation, setExplanation] = useState("");
  // other states
  const [stdin, setStdin] = useState(""); // legacy single-run input (kept for compatibility)
  const [problems, setProblems] = useState([]);
  const [theme, setTheme] = useState("vs-dark");
  const [searchOpen, setSearchOpen] = useState(false);
  const [searchQuery, setSearchQuery] = useState("");
  const [aiSuggestions, setAiSuggestions] = useState([]);
  const [contextMenu, setContextMenu] = useState(null); // {x,y,file}
  const editorRef = useRef(null);
  const fileInputRef = useRef(null);

  // NEW: loading states
  const [isRunning, setIsRunning] = useState(false);
  const [isFixing, setIsFixing] = useState(false);
  const [isExplaining, setIsExplaining] = useState(false);

  // Always persist tree on change
  useEffect(() => {
    saveTree(tree);
  }, [tree]);

  // helpers
  const currentNode = getNodeByPath(tree, activePath);
  const langMeta =
    LANGUAGE_OPTIONS.find((l) => currentNode?.name?.endsWith(l.ext)) ||
    LANGUAGE_OPTIONS[0];

  // ---------- TREE helpers ----------
  const collectFolderPaths = (node, acc = []) => {
    if (!node) return acc;
    if (node.type === "folder") acc.push(node.path || "");
    node.children?.forEach((c) => collectFolderPaths(c, acc));
    return acc;
  };

  // ---------- File / Folder actions ----------
  const handleNewFile = () => {
    const filename = window.prompt("Filename (with extension):", "untitled.js");
    if (!filename) return;

    // Determine default parent
    const selected = getNodeByPath(tree, activePath);
    let parentPath = "";
    if (selected?.type === "folder") parentPath = selected.path;
    else if (selected?.type === "file") {
      const parts = selected.path.split("/").slice(0, -1);
      parentPath = parts.join("/");
    }

    const folders = collectFolderPaths(tree);
    const suggestion = parentPath || folders[0] || "";
    const chosen = window.prompt(
      `Parent folder (enter path). Available:\n${folders.join("\n")}\n\nLeave empty for root.`,
      suggestion
    );
    const targetParent = chosen == null ? parentPath : (chosen.trim() || "");

    const updated = addFile(tree, filename, targetParent);
    setTree(updated);

    const newPath = (targetParent ? targetParent + "/" : "") + filename;
    setActivePath(newPath);
  };

  const handleNewFolder = () => {
    const name = window.prompt("Folder name:", "new_folder");
    if (!name) return;
    const selected = getNodeByPath(tree, activePath);
    const parentPath = selected && selected.type === "folder" ? selected.path : "";
    const updated = addFolder(tree, name, parentPath);
    setTree(updated);
  };

  const handleRename = () => {
    if (!activePath) return;
    const node = getNodeByPath(tree, activePath);
    if (!node) return;
    const newName = window.prompt("New name:", node.name);
    if (!newName || newName === node.name) return;
    const updated = renameNode(tree, activePath, newName);
    setTree(updated);

    const parts = activePath.split("/");
    parts.pop();
    const parent = parts.join("/");
    const newPath = (parent ? parent + "/" : "") + newName;
    setActivePath(newPath);
  };

  const handleDelete = () => {
    if (!activePath) return;
    const node = getNodeByPath(tree, activePath);
    if (!node) return;

    if (node.type === "folder" && node.children?.length > 0) {
      const ok = window.confirm(`Folder "${node.name}" has ${node.children.length} items. Delete anyway?`);
      if (!ok) return;
    } else {
      const ok = window.confirm(`Delete "${node.name}"?`);
      if (!ok) return;
    }

    const updated = deleteNode(tree, activePath);
    setTree(updated);
    setActivePath("");
  };

  const downloadFile = () => {
    const node = getNodeByPath(tree, activePath);
    if (!node || node.type !== "file") return;
    const blob = new Blob([node.content || ""], { type: "text/plain;charset=utf-8" });
    const a = document.createElement("a");
    a.href = URL.createObjectURL(blob);
    a.download = node.name;
    a.click();
  };

  // Import file from user's machine into selected folder
  const handleImportFileClick = () => fileInputRef.current?.click();

  const handleFileInputChange = async (e) => {
    const f = e.target.files?.[0];
    if (!f) return;
    const text = await f.text();

    const selected = getNodeByPath(tree, activePath);
    let parentPath = "";
    if (selected?.type === "folder") parentPath = selected.path;
    else if (selected?.type === "file") parentPath = selected.path.split("/").slice(0, -1).join("");

    const updated = addFile(tree, f.name, parentPath);
    const newPath = (parentPath ? parentPath + "/" : "") + f.name;
    const finalTree = updateFileContent(updated, newPath, text);
    setTree(finalTree);
    setActivePath(newPath);
    e.target.value = "";
  };

  // ---------- Terminal/Run logic (interactive) ----------
  // We will accumulate stdin in `accumStdin`. On initial run we clear it.
  // When backend returns output containing cues that input is requested, set awaitingInput=true.
  // When user types into terminal prompt and presses Enter, append that input to accumStdin + "\n",
  // then re-run the program with updated accumStdin. Repeat until no input cues.

  const resetTerminal = () => {
    setTerminalLines([]);
    setTerminalInput("");
    setAccumStdin("");
    setAwaitingInput(false);
  };

  const appendTerminal = (text) => {
    setTerminalLines((prev) => [...prev, text]);
  };

  // helper: detect input calls in source (python/java/js)
function codeNeedsInput(code, langId) {
  if (!code) return false;
  try {
    const c = code.toString();
    if (langId === "python") {
      return /\binput\s*\(/i.test(c);
    }
    if (langId === "java") {
      return /\bScanner\s*\(|\bnext(Int|Line|Double|())\b/i.test(c) || /\bSystem\.console\(\)/i.test(c);
    }
    if (langId === "javascript") {
      // node.js stdin reads or prompt usage heuristics
      return /process\.stdin|readline|prompt\(|window\.prompt/i.test(c);
    }
    // fallback: look for common words
    return /\binput\b|\bScanner\b|\bnextInt\b|prompt\(/i.test(c);
  } catch {
    return false;
  }
}

  const handleRun = async () => {
  const node = getNodeByPath(tree, activePath);
  if (!node || node.type !== "file") {
    setOutput("Select a file to run.");
    return;
  }
  const selectedLang = LANGUAGE_OPTIONS.find((l) => node.name.endsWith(l.ext))?.id;
  if (!selectedLang || !RUNNABLE_LANGS.includes(selectedLang)) {
    setOutput(`⚠️ Run not supported for this file type.`);
    return;
  }

  // If code likely needs input and accumStdin is empty, ask for initial input
  const needs = codeNeedsInput(node.content, selectedLang);
  if (needs && !accumStdin) {
    // collect multi-line input: user can paste multiple lines separated by \n
    const userText = window.prompt(
      "This program appears to request console input (e.g. input() / Scanner).\n\nEnter input lines separated by a newline (\\n). Leave empty to run without input.",
      ""
    );
    if (userText == null) {
      // user pressed cancel: proceed but warn
      appendTerminal("[Run cancelled by user]");
      return;
    }
    // userText may contain literal backslash-n if pasted; keep it as-is.
    // Normalize: if the user typed using Enter, it's already multi-line.
    const prepared = userText.replace(/\\n/g, "\n");
    setAccumStdin(prepared);
  }

    // clear terminal state and start a fresh run
    resetTerminal();
    setIsRunning(true);
    setProblems([]);
    setOutput("");
    try {
      // call backend with current accumStdin (empty on first run)
      const res = await runCode(node.content, selectedLang, accumStdin || stdin || "");
      const out = res.output ?? "";
      setOutput(out);
      appendTerminal(out);
      setProblems(res.error ? parseProblems(res.output) : []);

      if (outputLooksForInput(out)) {
        // program likely wants input: show prompt
        setAwaitingInput(true);
      } else {
        setAwaitingInput(false);
      }
    } catch (err) {
      const e = String(err);
      setOutput(e);
      appendTerminal(e);
      setAwaitingInput(false);
    } finally {
      setIsRunning(false);
    }
  };

  // Called when user types input into terminal and presses Enter
  const sendTerminalInput = async () => {
  if (!currentNode || currentNode.type !== "file") {
    appendTerminal("No file selected.");
    setAwaitingInput(false);
    return;
  }

  // If not already in awaitingInput (heuristic missed), still allow sending input:
  if (!awaitingInput && !isRunning && terminalInput.trim()) {
    appendTerminal("[Info] Sending input to program (re-run).");
  }

  const userText = terminalInput;
  appendTerminal(`> ${userText}`);
  const newAccum = (accumStdin || "") + userText + "\n";
  setAccumStdin(newAccum);
  setTerminalInput("");
  setIsRunning(true);
  try {
    const selectedLang = LANGUAGE_OPTIONS.find((l) => currentNode.name.endsWith(l.ext))?.id;
    const res = await runCode(currentNode.content, selectedLang, newAccum);
    const out = res.output ?? "";
    setOutput(out);
    appendTerminal(out);
    setProblems(res.error ? parseProblems(res.output) : []);
    if (outputLooksForInput(out)) {
      setAwaitingInput(true);
    } else {
      setAwaitingInput(false);
    }
  } catch (err) {
    appendTerminal(String(err));
    setAwaitingInput(false);
  } finally {
    setIsRunning(false);
  }
};

  // Allow pressing Enter to send input
  const onTerminalKeyDown = (e) => {
    if (e.key === "Enter") {
      e.preventDefault();
      if (!awaitingInput) return;
      sendTerminalInput();
    }
  };

  // ---------- Agent functions ----------
  const handleAskFix = async () => {
    const node = getNodeByPath(tree, activePath);
    if (!node || node.type !== "file") {
      setOutput("Select a file to apply fix.");
      return;
    }
    setIsFixing(true);
    try {
      const userHint = prompt.trim() ? `User request: ${prompt}` : "";
      const reply = await askAgent(
        `Improve, debug, or refactor this ${LANGUAGE_OPTIONS.find((l) => node.name.endsWith(l.ext))?.id || "file"} file.\n${userHint}\nReturn ONLY updated code, no explanation.\n\nCODE:\n${node.content}`
      );
      const updatedTree = updateFileContent(tree, node.path, reply);
      setTree(updatedTree);
    } catch (err) {
      setOutput(String(err));
    } finally {
      setIsFixing(false);
    }
  };

  const handleExplainSelection = async () => {
    const node = getNodeByPath(tree, activePath);
    if (!node || node.type !== "file") {
      setExplanation("Select a file to explain.");
      return;
    }
    setIsExplaining(true);
    try {
      const editor = editorRef.current;
      let selectedCode = "";
      try {
        selectedCode = editor?.getModel()?.getValueInRange(editor.getSelection()) || "";
      } catch {}
      const code = selectedCode.trim() || node.content;
      const userHint = prompt.trim() ? `Focus on: ${prompt}` : "Give a clear and simple explanation.";
      const reply = await askAgent(
        `Explain what this code does, any risks, and improvements.\n${userHint}\n\nCODE:\n${code}`
      );
      setExplanation(reply);
    } catch (err) {
      setExplanation(String(err));
    } finally {
      setIsExplaining(false);
    }
  };

  // AI suggestions for continuation (simple)
  const fetchAiSuggestions = async (code) => {
    if (!code?.trim()) return;
    try {
      const reply = await askAgent(`Suggest possible next lines for continuation. Return 3 short snippets.\n${code}`);
      setAiSuggestions(reply.split("\n").filter((l) => l.trim()));
    } catch {
      // ignore suggestion errors
    }
  };

  // ---------- Search ----------
  const handleSearchToggle = () => setSearchOpen(!searchOpen);

  const handleSearchNow = () => {
    if (!searchQuery) return;
    const results = searchTree(tree, searchQuery);
    alert(`Found ${results.length} results:\n` + JSON.stringify(results, null, 2));
  };

  // ---------- Editor change ----------
  const updateActiveFileContent = (value) => {
    const node = getNodeByPath(tree, activePath);
    if (!node) return;
    const updated = updateFileContent(tree, activePath, value ?? "");
    setTree(updated);
  };

  // ---------- Render Tree (inside component) ----------
  const renderTree = (node, depth = 0) => {
    const isActive = node.path === activePath;
    return (
      <div key={node.path || node.name} style={{ paddingLeft: depth * 10 }}>
        <div
          className={`tree-item ${node.type} ${isActive ? "ide-file-item-active" : ""}`}
          onClick={() => setActivePath(node.path)}
          onContextMenu={(e) => {
            e.preventDefault();
            setActivePath(node.path);
            setContextMenu({ x: e.pageX, y: e.pageY, file: node.path });
          }}
          style={{ display: "flex", alignItems: "center", gap: 8 }}
        >
          <span style={{ width: 18 }}>{node.type === "folder" ? "📁" : "📄"}</span>
          <span className="ide-file-name">{node.name}</span>
        </div>

        {node.children && node.children.map((c) => renderTree(c, depth + 1))}
      </div>
    );
  };

  // any loading?
  const anyLoading = isRunning || isFixing || isExplaining;

  // ---------- JSX UI ----------
  return (
    <div className={`ide-root ${theme === "vs-dark" ? "ide-dark" : "ide-light"}`}>
      {/* Hidden file input for import */}
      <input ref={fileInputRef} id="file-import-input" type="file" style={{ display: "none" }} onChange={handleFileInputChange} />

      {/* Top menu */}
      <div className="ide-menubar">
        <div className="ide-menubar-left">
          <span className="ide-logo">⚙️ DevMate IDE</span>

          <button onClick={handleNewFile} disabled={anyLoading}>📄 New File</button>
          <button onClick={handleNewFolder} disabled={anyLoading}>📁 New Folder</button>
          <button onClick={handleRename} disabled={anyLoading}>✏️ Rename</button>
          <button onClick={handleDelete} disabled={anyLoading}>🗑 Delete</button>
          <button onClick={downloadFile} disabled={anyLoading}>📥 Download</button>
          <button onClick={() => downloadProjectZip()} disabled={anyLoading}>📦 ZIP</button>
          <button onClick={handleImportFileClick} disabled={anyLoading}>📤 Import File</button>
        </div>

        <div className="ide-menubar-right">
          <button onClick={handleSearchToggle} disabled={anyLoading}>🔍 Search</button>
          <button onClick={handleRun} disabled={isRunning || anyLoading}>{isRunning ? "⏳ Running..." : "▶ Run"}</button>
          <button onClick={handleAskFix} disabled={isFixing || anyLoading}>{isFixing ? "⏳ Fixing..." : "🤖 Fix"}</button>
          <button onClick={handleExplainSelection} disabled={isExplaining || anyLoading}>{isExplaining ? "⏳ Explaining..." : "📖 Explain"}</button>
          <button onClick={() => setTheme((t) => (t === "vs-dark" ? "light" : "vs-dark"))} disabled={anyLoading}>
            {theme === "vs-dark" ? "☀️" : "🌙"}
          </button>
        </div>
      </div>

      {/* Indeterminate progress bar under menubar when busy */}
      {anyLoading && (
        <div className="ide-progress-wrap">
          <div className="ide-progress" />
        </div>
      )}

      {/* Body */}
      <div className="ide-body">
        {/* Sidebar */}
        <div className="ide-sidebar">
          <div className="ide-sidebar-header">
            <span>EXPLORER</span>
            <button className="ide-icon-button" onClick={handleNewFile} title="New File" disabled={anyLoading}>＋</button>
          </div>
          <div className="ide-file-list" style={{ padding: 6 }}>{renderTree(tree)}</div>
        </div>

        {/* Main (editor + bottom panels) */}
        <div className="ide-main">
          <div className="ide-editor-wrapper">
            <Editor
              height="100%"
              theme={theme}
              language={langMeta.monaco}
              value={currentNode?.content || ""}
              onChange={updateActiveFileContent}
              onMount={(editor) => (editorRef.current = editor)}
              onBlur={() => fetchAiSuggestions(currentNode?.content)}
              options={{ minimap: { enabled: true }, fontSize: 14, scrollBeyondLastLine: false }}
            />
          </div>

          {/* AI inline suggestions popup */}
          {aiSuggestions.length > 0 && (
            <div className="ai-popup">
              {aiSuggestions.map((s, i) => (
                <div key={i} className="ai-suggest" onClick={() => updateActiveFileContent((currentNode?.content || "") + "\n" + s)}>{s}</div>
              ))}
            </div>
          )}

          {/* Bottom panels */}
          <div className="ide-panels">
            {/* Terminal output */}
            <div className="ide-output-terminal" style={{ marginBottom: 8 }}>
              <div style={{ fontSize: 12, color: "#ccc", marginBottom: 6 }}>Terminal</div>
              <div className="terminal-content" style={{ background: "#000", color: "#0f0", padding: 8, borderRadius: 6, maxHeight: 220, overflowY: "auto", whiteSpace: "pre-wrap", fontFamily: "Consolas, monospace" }}>
                {terminalLines.length === 0 ? <div style={{ color: "#999" }}>[Program output will appear here]</div> : terminalLines.map((ln, i) => <div key={i}>{ln}</div>)}
                {awaitingInput && <div style={{ color: "#fff" }}>&nbsp;</div>}
              </div>

              {/* Terminal input (shown only when program asks input) */}
              {awaitingInput ? (
                <div style={{ display: "flex", gap: 6, marginTop: 6 }}>
                  <input
                    className="ide-input-box"
                    placeholder="Type input and press Enter..."
                    value={terminalInput}
                    onChange={(e) => setTerminalInput(e.target.value)}
                    onKeyDown={onTerminalKeyDown}
                    disabled={!awaitingInput || isRunning}
                  />
                  <button onClick={sendTerminalInput} disabled={!awaitingInput || isRunning} className="ide-button">Send</button>
                </div>
              ) : (
                // If not awaiting input, show legacy single-run input + hint to run for interactive programs
                <div style={{ display: "flex", gap: 6, marginTop: 6 }}>
                  <input className="ide-input-box" placeholder="(Optional) Program input for single-run" value={stdin} onChange={(e) => setStdin(e.target.value)} />
                  <div style={{ alignSelf: "center", color: "#999", fontSize: 12 }}>Press Run → to execute</div>
                </div>
              )}
            </div>

            {/* Problems */}
            {problems.length > 0 && (
              <div className="ide-problems-panel">
                <div>🚨 Problems ({problems.length})</div>
                {problems.map((p, i) => <div key={i}>{p.path}:{p.line} — {p.message}</div>)}
              </div>
            )}
          </div>
        </div>

        {/* Right AI panel */}
        <div className="ide-right-panel">
          <div className="ide-ai-header">🤖 AI Assistant</div>

          <div className="ide-ai-section">
            <label className="ide-ai-label">Instruction</label>
            <textarea className="ide-agent-textarea" placeholder="Ask the AI (optimize, add tests, convert, etc.)" value={prompt} onChange={(e) => setPrompt(e.target.value)} />
          </div>

          <div className="ide-ai-buttons">
            <button onClick={handleAskFix} disabled={isFixing || anyLoading}>{isFixing ? "⏳ Apply Fix" : "💡 Apply Fix"}</button>
            <button onClick={handleExplainSelection} disabled={isExplaining || anyLoading}>{isExplaining ? "⏳ Explaining" : "📖 Explain Code"}</button>
          </div>

          {explanation && (
            <div className="ide-ai-section">
              <label className="ide-ai-label">Explanation</label>
              <div className="ide-explain">{explanation}</div>
            </div>
          )}
        </div>
      </div>

      {/* Search dialog */}
      {searchOpen && (
        <div className="search-dialog">
          <input placeholder="Search text..." onChange={(e) => setSearchQuery(e.target.value)} />
          <button onClick={handleSearchNow}>Search</button>
        </div>
      )}

      {/* Context menu */}
      {contextMenu && (
        <div className="ide-context-menu" style={{ top: contextMenu.y, left: contextMenu.x }} onMouseLeave={() => setContextMenu(null)}>
          <div onClick={() => { setContextMenu(null); handleRename(); }}>✏️ Rename</div>
          <div onClick={() => { setContextMenu(null); handleDelete(); }}>🗑 Delete</div>
          <div onClick={() => { setContextMenu(null); downloadFile(); }}>📥 Download</div>
        </div>
      )}
    </div>
  );
}

export default App;