/* --- DOM refs --- */
const form = document.getElementById("review-form");
const urlInput = document.getElementById("url-input");
const submitBtn = document.getElementById("submit-btn");
const inputError = document.getElementById("input-error");
const metaEl = document.getElementById("meta");
const metaRepo = document.getElementById("meta-repo");
const metaPath = document.getElementById("meta-path");
const metaBranch = document.getElementById("meta-branch");
const tabsEl = document.getElementById("tabs");
const tabContent = document.getElementById("tab-content");
const streamError = document.getElementById("stream-error");
const tabButtons = document.querySelectorAll(".tab");

const GITHUB_BLOB_RE = /^https?:\/\/github\.com\/[^/]+\/[^/]+\/blob\/[^/]+\/.+$/;

/* --- Section parsing --- */

const SECTION_KEYS = ["summary", "quality", "performance", "security", "suggestions", "verdicts"];

// Maps heading text (lowercased) to our section key
const HEADING_MAP = {
  summary: "summary",
  "code quality": "quality",
  performance: "performance",
  security: "security",
  suggestions: "suggestions",
  verdicts: "verdicts",
};

function parseSections(markdown) {
  const sections = {};
  let currentKey = null;

  for (const line of markdown.split("\n")) {
    const m = line.match(/^## (.+)$/);
    if (m) {
      const title = m[1].trim().toLowerCase();
      const matched = Object.entries(HEADING_MAP).find(([kw]) => title.includes(kw));
      if (matched) {
        currentKey = matched[1];
        sections[currentKey] = "";
        continue;
      }
    }
    if (currentKey) {
      sections[currentKey] = (sections[currentKey] || "") + line + "\n";
    }
  }
  return sections;
}

// Detect which section the model is currently writing to (last matched heading)
function detectCurrentSection(markdown) {
  let last = null;
  for (const line of markdown.split("\n")) {
    const m = line.match(/^## (.+)$/);
    if (m) {
      const title = m[1].trim().toLowerCase();
      const matched = Object.entries(HEADING_MAP).find(([kw]) => title.includes(kw));
      if (matched) last = matched[1];
    }
  }
  return last;
}

/* --- Diff-aware marked renderer --- */

function escapeHtml(str) {
  return str.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;").replace(/"/g, "&quot;");
}

function isDiffContent(text) {
  const lines = text.split("\n");
  let diffLines = 0;
  for (const l of lines) {
    if (l.startsWith("+") || l.startsWith("-") || l.startsWith("@@")) diffLines++;
  }
  return diffLines >= 2;
}

function renderDiffBlock(text) {
  const lines = text.split("\n").map((line) => {
    const escaped = escapeHtml(line);
    if (line.startsWith("+++") || line.startsWith("---")) {
      return `<span class="diff-line diff-info">${escaped}</span>`;
    }
    if (line.startsWith("+")) {
      return `<span class="diff-line diff-add">${escaped}</span>`;
    }
    if (line.startsWith("-")) {
      return `<span class="diff-line diff-del">${escaped}</span>`;
    }
    if (line.startsWith("@@")) {
      return `<span class="diff-line diff-info">${escaped}</span>`;
    }
    return `<span class="diff-line diff-neutral">${escaped}</span>`;
  });
  return `<pre class="diff-block"><code>${lines.join("")}</code></pre>`;
}

const renderer = {
  code({ text, lang, language }) {
    const codeLang = (lang || language || "").toLowerCase().trim();
    // Render as diff if tagged as diff OR if content looks like a diff
    if (codeLang === "diff" || (!codeLang && isDiffContent(text))) {
      return renderDiffBlock(text);
    }
    const langClass = codeLang ? ` class="language-${escapeHtml(codeLang)}"` : "";
    return `<pre><code${langClass}>${escapeHtml(text)}</code></pre>`;
  },
};

marked.use({ renderer });

function renderMarkdown(md) {
  return DOMPurify.sanitize(marked.parse(md));
}

/* --- Tab management --- */

let activeTab = "summary";
let manualSwitch = false;
let currentSections = {};

tabButtons.forEach((btn) => {
  btn.addEventListener("click", () => {
    manualSwitch = true;
    setActiveTab(btn.dataset.section);
    renderActiveTab();
  });
});

function setActiveTab(section) {
  activeTab = section;
  tabButtons.forEach((btn) => {
    btn.classList.toggle("active", btn.dataset.section === section);
  });
}

function renderActiveTab() {
  const md = currentSections[activeTab] || "";
  if (md.trim()) {
    tabContent.innerHTML = renderMarkdown(md);
    tabContent.classList.remove("tab-content-empty");
  } else {
    tabContent.textContent = "Waiting for content\u2026";
    tabContent.classList.add("tab-content-empty");
  }
}

function updateTabs(sections, currentStreamSection) {
  currentSections = sections;

  // Mark tabs that have content + which one is streaming
  tabButtons.forEach((btn) => {
    const key = btn.dataset.section;
    btn.classList.toggle("has-content", !!sections[key]?.trim());
    btn.classList.toggle("streaming", key === currentStreamSection);
  });

  // Auto-switch to the section currently being written (unless user clicked a tab)
  if (!manualSwitch && currentStreamSection) {
    setActiveTab(currentStreamSection);
  }

  renderActiveTab();
}

/* --- Review flow --- */

let currentSource = null;

form.addEventListener("submit", (e) => {
  e.preventDefault();
  startReview();
});

/* --- Sample buttons --- */

document.querySelectorAll(".sample-btn").forEach((btn) => {
  btn.addEventListener("click", () => {
    urlInput.value = btn.dataset.url;
    startReview();
  });
});

function startReview() {
  const url = urlInput.value.trim();

  // Reset
  inputError.hidden = true;
  streamError.hidden = true;
  metaEl.hidden = true;
  tabsEl.hidden = true;
  tabContent.textContent = "";
  manualSwitch = false;
  setActiveTab("summary");
  tabButtons.forEach((btn) => {
    btn.classList.remove("has-content", "streaming");
  });

  if (!url) { showInputError("Please enter a GitHub file URL."); return; }
  if (!GITHUB_BLOB_RE.test(url)) {
    showInputError("URL must be a GitHub blob URL (e.g. https://github.com/owner/repo/blob/main/file.js).");
    return;
  }

  if (currentSource) { currentSource.close(); currentSource = null; }
  setLoading(true);

  let markdown = "";
  const source = new EventSource(`/api/review?url=${encodeURIComponent(url)}`);
  currentSource = source;

  source.addEventListener("meta", (e) => {
    const data = JSON.parse(e.data);
    metaRepo.textContent = `${data.owner}/${data.repo}`;
    metaPath.textContent = data.path;
    metaBranch.textContent = data.branch;
    metaEl.hidden = false;
    tabsEl.hidden = false;
    tabContent.classList.add("is-streaming");
  });

  source.addEventListener("content", (e) => {
    const data = JSON.parse(e.data);
    markdown += data.text;
    const sections = parseSections(markdown);
    const current = detectCurrentSection(markdown);
    updateTabs(sections, current);
  });

  source.addEventListener("done", () => {
    cleanup();
    // Final render with no streaming section
    const sections = parseSections(markdown);
    updateTabs(sections, null);
  });

  source.addEventListener("error", (e) => {
    if (e.data) {
      const data = JSON.parse(e.data);
      showStreamError(data.message);
    } else {
      showStreamError("Connection lost. Please try again.");
    }
    cleanup();
  });

  function cleanup() {
    source.close();
    currentSource = null;
    setLoading(false);
    tabContent.classList.remove("is-streaming");
    tabButtons.forEach((btn) => btn.classList.remove("streaming"));
  }
}

/* --- Helpers --- */

function setLoading(on) {
  submitBtn.disabled = on;
  submitBtn.textContent = on ? "Reviewing\u2026" : "Review Code";
  document.body.classList.toggle("loading", on);
}

function showInputError(msg) {
  inputError.textContent = msg;
  inputError.hidden = false;
}

function showStreamError(msg) {
  streamError.textContent = msg;
  streamError.hidden = false;
}