// src/App.js
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";
import "xterm/css/xterm.css";
import XTerm from "./Terminal"; // your existing wrapper

// =================== 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"];

// =================== Heuristics ===================
// patterns that indicate program is waiting for input
function outputLooksForInput(output) {
  if (!output) return false;
  const o = output.toString();
  const patterns = [
    /enter.*:/i,
    /input.*:/i,
    /please enter/i,
    /scanner/i,
    /press enter/i,
    /: $/,
    /:\n$/,
    /> $/,
    /awaiting input/i,
    /provide input/i,
    /stdin/i,
    /enter a value/i,
  ];
  return patterns.some((p) => p.test(o));
}

// code-level heuristics to detect input calls
function codeNeedsInput(code, langId) {
  if (!code) return false;
  try {
    const c = code.toString();
    if (langId === "python") {
      if (/\binput\s*\(/i.test(c)) return true;
      if (/\bsys\.stdin\.(read|readline|readlines)\s*\(/i.test(c)) return true;
      if (/\braw_input\s*\(/i.test(c)) return true;
    }
    if (langId === "java") {
      if (/\bScanner\s*\(/i.test(c)) return true;
      if (/\bBufferedReader\b.*readLine/i.test(c)) return true;
      if (/\bSystem\.console\(\)/i.test(c)) return true;
      if (/\bnext(Int|Line|Double|)\b/i.test(c)) return true;
    }
    if (langId === "javascript") {
      if (/process\.stdin|readline|readlineSync|prompt\(|require\(['"]readline['"]\)/i.test(c)) return true;
    }
    if (langId === "cpp" || langId === "c") {
      if (/\bscanf\s*\(/i.test(c)) return true;
      if (/\bstd::cin\b|cin\s*>>/i.test(c)) return true;
      if (/\bgets?\s*\(/i.test(c)) return true;
    }
    if (/\binput\b|\bscanf\b|\bscanf_s\b|\bcin\b|\bScanner\b|readLine|readline/i.test(c)) return true;
    return false;
  } catch {
    return false;
  }
}

// Helper: focus xterm's hidden textarea (works with xterm.js default markup)
function focusXtermHelper() {
  setTimeout(() => {
    const ta = document.querySelector("#terminal-container .xterm-helper-textarea");
    if (ta) {
      try {
        ta.focus();
        const len = ta.value?.length ?? 0;
        ta.setSelectionRange(len, len);
      } catch {}
    } else {
      const cont = document.getElementById("terminal-container");
      if (cont) cont.focus();
    }
  }, 120);
}

// =================== APP ===================
function App() {
  // ----- file tree + selection -----
  const [tree, setTree] = useState(loadTree());
  const [activePath, setActivePath] = useState("main.py");

  // ----- terminal / interactive state -----
  const [accumStdin, setAccumStdin] = useState(""); // accumulated input for interactive runs
  const [awaitingInput, setAwaitingInput] = useState(false);
  const [terminalLines, setTerminalLines] = useState([]); // visible lines in terminal area
  const [output, setOutput] = useState(""); // "write" prop for XTerm (Terminal component picks this up)
  const [interactivePromptShown, setInteractivePromptShown] = useState(false);

  // ----- AI + editor state -----
  const [prompt, setPrompt] = useState("");
  const [explanation, setExplanation] = useState("");
  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);
  const [isRunning, setIsRunning] = useState(false);
  const [isFixing, setIsFixing] = useState(false);
  const [isExplaining, setIsExplaining] = useState(false);

  // refs & helpers
  const editorRef = useRef(null);
  const fileInputRef = useRef(null);

  useEffect(() => {
    saveTree(tree);
  }, [tree]);

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

  // ---------- File / Folder actions ----------
  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;
  };

  const handleNewFile = () => {
    const filename = window.prompt("Filename (with extension):", "untitled.js");
    if (!filename) return;
    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();
  };

  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 helpers ----------
  const appendTerminal = (text) => {
    // push to visible lines and set `output` (which Terminal writes)
    setTerminalLines((prev) => {
      const next = [...prev, text];
      // also keep the XTerm single-output prop to trigger Terminal.writeln
      setOutput(text);
      return next;
    });
  };

  const clearTerminal = () => {
    // ANSI sequence to clear screen + move cursor home (xterm will honor)
    setTerminalLines([]);
    setOutput("\x1b[2J\x1b[H");
    setAccumStdin("");
    setAwaitingInput(false);
    setInteractivePromptShown(false);
  };

  const resetTerminal = (keepAccum = false) => {
    setTerminalLines([]);
    setOutput("");
    if (!keepAccum) {
      setAccumStdin("");
    }
    setAwaitingInput(false);
    setInteractivePromptShown(false);
  };

  // Unified runner used when terminal provides input (or small input)
  const runCodeWithUpdatedInput = async (inputLine) => {
    if (typeof inputLine !== "string") inputLine = String(inputLine || "");
    const trimmed = inputLine.replace(/\r$/, "");
    // if user pressed Enter with empty line and no accum, ignore
    if (trimmed.length === 0 && !accumStdin) {
      return;
    }

    // append newline like console
    const newAccum = (accumStdin || "") + trimmed + "\n";
    setAccumStdin(newAccum);
    setInteractivePromptShown(false);

    const node = getNodeByPath(tree, activePath);
    if (!node || node.type !== "file") {
      appendTerminal("[Error] No file selected to run.");
      setAwaitingInput(false);
      return;
    }

    const selectedLang = LANGUAGE_OPTIONS.find((l) => node.name.endsWith(l.ext))?.id;
    if (!selectedLang || !RUNNABLE_LANGS.includes(selectedLang)) {
      appendTerminal(`[Error] Run not supported for ${node.name}`);
      setAwaitingInput(false);
      return;
    }

    setIsRunning(true);
    try {
      const res = await runCode(node.content, selectedLang, newAccum);
      const out = res.output ?? "";
      if (out) appendTerminal(out);
      setProblems(res.error ? parseProblems(res.output) : []);
      if (outputLooksForInput(out)) {
        setAwaitingInput(true);
        focusXtermHelper();
      } else {
        setAwaitingInput(false);
        setAccumStdin(""); // finished -> clear accumulated input so next Run is fresh
      }
    } catch (err) {
      appendTerminal(String(err));
      setAwaitingInput(true);
    } finally {
      setIsRunning(false);
    }
  };

  // ---------- Initial Run handler (fresh runs) ----------
  const handleRun = async () => {
    const node = getNodeByPath(tree, activePath);
    if (!node || node.type !== "file") {
      appendTerminal("Select a file to run.");
      return;
    }

    const selectedLang = LANGUAGE_OPTIONS.find((l) => node.name.endsWith(l.ext))?.id;
    if (!selectedLang || !RUNNABLE_LANGS.includes(selectedLang)) {
      appendTerminal(`⚠️ Run not supported for this file type.`);
      return;
    }

    // Force fresh run: clear accumulated input and terminal
    setAccumStdin("");
    resetTerminal(false);
    setAwaitingInput(false);
    setInteractivePromptShown(false);

    const needs = codeNeedsInput(node.content, selectedLang);

    if (needs) {
      appendTerminal("[Interactive program detected — type input directly into the terminal]");
      setAwaitingInput(true);
      setInteractivePromptShown(true);
      focusXtermHelper();
      return; // wait for user's input to avoid EOFError
    }

    // Non-interactive: run immediately with empty stdin
    appendTerminal(`[Running (fresh)]`);
    setIsRunning(true);
    setProblems([]);
    try {
      const res = await runCode(node.content, selectedLang, "");
      const out = res.output ?? "";
      if (out) appendTerminal(out);
      setProblems(res.error ? parseProblems(res.output) : []);
      if (outputLooksForInput(out)) {
        setAwaitingInput(true);
        focusXtermHelper();
      } else {
        setAwaitingInput(false);
        setAccumStdin("");
      }
    } catch (err) {
      appendTerminal(String(err));
      setAwaitingInput(true);
      focusXtermHelper();
    } finally {
      setIsRunning(false);
    }
  };

  // ---------- Agent functions ----------
  const handleAskFix = async () => {
    const node = getNodeByPath(tree, activePath);
    if (!node || node.type !== "file") {
      appendTerminal("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);
      appendTerminal("[AI] Applied fixes to file.");
    } catch (err) {
      appendTerminal(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
  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
    }
  };

  // ---------- 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
  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>
    );
  };

  const anyLoading = isRunning || isFixing || isExplaining;

  // ---------- JSX ----------
  return (
    <div
      className={`ide-root ${theme === "vs-dark" ? "ide-dark" : "ide-light"}`}
      style={{ overflowX: "hidden" }} // prevent horizontal white gap / scroller issue
    >
      <input ref={fileInputRef} id="file-import-input" type="file" style={{ display: "none" }} onChange={handleFileInputChange} />

      <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>
          <button onClick={clearTerminal} disabled={anyLoading} title="Clear terminal">🧹 Clear</button>
        </div>
      </div>

      {(isRunning || isFixing || isExplaining) && (
        <div className="ide-progress-wrap">
          <div className="ide-progress" />
        </div>
      )}

      <div className="ide-body">
        <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>

        <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>

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

          <div className="ide-panels">
            <div style={{ marginBottom: 8 }}>
              <div style={{ fontSize: 12, color: "#ccc", marginBottom: 6 }}>Terminal</div>

              <XTerm
                output={output}
                onData={(line) => {
                  // line is the typed content (no CR), pass to unified runner
                  const trimmed = (line || "").replace(/\r$/, "");
                  if (!trimmed && !awaitingInput) {
                    // nothing typed and not expecting input
                    return;
                  }
                  runCodeWithUpdatedInput(trimmed);
                }}
              />

              {awaitingInput && (
                <div style={{ marginTop: 8, padding: 8, background: "#252526", border: "1px solid #333", borderRadius: 6 }}>
                  <div style={{ marginBottom: 6, color: "#ddd" }}>
                    This program appears to be interactive and requires console input.
                  </div>
                  <div style={{ display: "flex", gap: 8 }}>
                    <button onClick={() => { focusXtermHelper(); }} className="ide-button">▶ Focus Terminal</button>
                    <button onClick={() => { resetTerminal(true); appendTerminal("[Interactive session started — type into the terminal]"); setAwaitingInput(true); focusXtermHelper(); }} className="ide-button">▶ Start interactive session</button>
                    <div style={{ color: "#999", alignSelf: "center" }}>Type & press Enter in terminal.</div>
                  </div>
                </div>
              )}
            </div>

            {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>

        <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>

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

      {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;