document.addEventListener("DOMContentLoaded", () => {
  // --- Constants ---
  const GITHUB_TOKEN_KEY = "github_access_token";

  // --- DOM Element Cache ---
  const docForm = document.getElementById("doc-form");
  const submitBtn = document.getElementById("submit-btn");
  const authSection = document.getElementById("auth-section");
  const mainContent = document.getElementById("main-content");
  const githubLoginBtn = document.getElementById("github-login-btn");
  const selectZipBtn = document.getElementById("select-zip-btn");
  const selectGithubBtn = document.getElementById("select-github-btn");
  const zipInputs = document.getElementById("zip-inputs");
  const githubInputs = document.getElementById("github-inputs");
  const zipFileInput = document.getElementById("zip-file");
  const repoSelect = document.getElementById("repo-select");
  const baseBranchSelect = document.getElementById("base-branch-select");
  const newBranchInput = document.getElementById("new-branch-input");
  const branchNameError = document.getElementById("branch-name-error");
  const fileTreeContainer = document.getElementById("file-tree-container");
  const fileTree = document.getElementById("file-tree");
  const liveProgressView = document.getElementById("live-progress-view");
  const resultSection = document.getElementById("result-section");
  const resultLink = document.getElementById("result-link");
  const logOutput = document.getElementById("log-output");

  // --- Helper Functions ---
  const showView = (viewId) => {
    [authSection, mainContent, liveProgressView, resultSection].forEach((el) =>
      el.classList.add("hidden")
    );
    document.getElementById(viewId).classList.remove("hidden");
  };
  const sanitizeForId = (str) =>
    `subtask-${str.replace(/[^a-zA-Z0-9-]/g, "-")}`;
  const resetProgressView = () => {
    document
      .querySelectorAll(".phase-item")
      .forEach((item) => (item.dataset.status = "pending"));
    document
      .querySelectorAll(".subtask-list")
      .forEach((list) => (list.innerHTML = ""));
    logOutput.textContent = "";
  };
  const createTreeHtml = (nodes, pathPrefix = "") => {
    let html = "<ul>";
    nodes.forEach((node) => {
      const fullPath = pathPrefix ? `${pathPrefix}/${node.name}` : node.name;
      const isDir = !!node.children;
      html += `<li><input type="checkbox" name="exclude_paths" value="${fullPath}" id="cb-${fullPath}"> <label for="cb-${fullPath}"><strong>${
        node.name
      }${isDir ? "/" : ""}</strong></label>`;
      if (isDir) html += createTreeHtml(node.children, fullPath);
      html += "</li>";
    });
    html += "</ul>";
    return html;
  };

  // --- Core Logic (unchanged app behavior) ---
  const checkBranchName = async () => {
    const repoFullName = repoSelect.value;
    const branchName = newBranchInput.value.trim();
    const token = localStorage.getItem(GITHUB_TOKEN_KEY);

    branchNameError.textContent = "";
    branchNameError.style.display = "none";

    if (
      !repoFullName ||
      !branchName ||
      !token ||
      !selectGithubBtn.classList.contains("active")
    ) {
      submitBtn.disabled = false;
      return;
    }

    submitBtn.disabled = true;
    submitBtn
      .querySelector(".btn-inner span:last-child")
      ?.replaceWith(document.createTextNode("Checking branch..."));

    try {
      const response = await fetch(
        `/api/github/branch-exists?repo_full_name=${encodeURIComponent(
          repoFullName
        )}&branch_name=${encodeURIComponent(branchName)}`,
        {
          headers: { Authorization: `Bearer ${token}` },
        }
      );

      if (!response.ok) {
        const errData = await response.json();
        throw new Error(errData.detail || `Server error: ${response.status}`);
      }

      const data = await response.json();
      if (data.exists) {
        branchNameError.textContent = `Branch '${branchName}' already exists. Please choose another name.`;
        branchNameError.style.display = "block";
        submitBtn.disabled = true;
      } else {
        submitBtn.disabled = false;
      }
    } catch (error) {
      console.error("Error checking branch name:", error);
      branchNameError.textContent = `Could not verify branch name. ${error.message}`;
      branchNameError.style.display = "block";
      submitBtn.disabled = false; // Allow submission, server will catch it if it's a real issue.
    } finally {
      // Restore button text
      const inner = submitBtn.querySelector(".btn-inner");
      if (inner) {
        inner.innerHTML =
          '<span class="loader" aria-hidden="true"></span><span>Generate Documentation</span>';
      }
    }
  };

  const handleAuth = () => {
    const urlParams = new URLSearchParams(window.location.search);
    const token = urlParams.get("token");
    const error = urlParams.get("error");

    if (error) alert(`Authentication failed: ${error}`);
    if (token && token !== "None")
      localStorage.setItem(GITHUB_TOKEN_KEY, token);
    window.history.replaceState({}, document.title, "/");

    if (localStorage.getItem(GITHUB_TOKEN_KEY)) {
      // --- Logged In User Flow ---
      showView("main-content");
      fetchGithubRepos();
      switchMode("github");
    } else {
      // --- Logged Out User Flow (FIXED) ---
      // 1. Always show the main form content, not the separate auth screen.
      // This makes the form, including ZIP upload, always accessible.
      showView("main-content");

      // 2. The auth section with the login button should be visible.
      // We manually un-hide it because showView is designed to show only one view.
      authSection.classList.remove("hidden");

      // 3. Default to ZIP mode and disable the GitHub tab.
      switchMode("zip");
      selectGithubBtn.disabled = true;
    }
  };

  const fetchGithubRepos = async () => {
    const token = localStorage.getItem(GITHUB_TOKEN_KEY);
    if (!token) return;

    try {
      const response = await fetch("/api/github/repos", {
        headers: { Authorization: `Bearer ${token}` },
      });
      if (response.status === 401) {
        localStorage.removeItem(GITHUB_TOKEN_KEY);
        alert("GitHub session expired. Please log in again.");
        handleAuth();
        return;
      }
      if (!response.ok) throw new Error("Failed to fetch repos");

      const repos = await response.json();
      repoSelect.innerHTML =
        '<option value="">-- Select a repository --</option>';
      repos.forEach((repo) => {
        const option = document.createElement("option");
        option.value = repo.full_name;
        option.textContent = repo.full_name;
        option.dataset.defaultBranch = repo.default_branch;
        repoSelect.appendChild(option);
      });
    } catch (error) {
      console.error(error);
    }
  };

  const fetchRepoBranches = async (repoFullName, defaultBranch) => {
    const token = localStorage.getItem(GITHUB_TOKEN_KEY);
    if (!token || !repoFullName) return;

    baseBranchSelect.innerHTML = "<option>Loading branches...</option>";
    baseBranchSelect.disabled = true;

    try {
      const response = await fetch(
        `/api/github/branches?repo_full_name=${repoFullName}`,
        {
          headers: { Authorization: `Bearer ${token}` },
        }
      );
      if (!response.ok) throw new Error("Failed to fetch branches");
      const branches = await response.json();

      baseBranchSelect.innerHTML = "";
      branches.forEach((branchName) => {
        const option = document.createElement("option");
        option.value = branchName;
        option.textContent = branchName;
        if (branchName === defaultBranch) option.selected = true;
        baseBranchSelect.appendChild(option);
      });
    } catch (error) {
      console.error(error);
      baseBranchSelect.innerHTML = `<option>Error loading branches</option>`;
    } finally {
      baseBranchSelect.disabled = false;
    }
  };

  const fetchAndBuildTree = async (repoFullName, branch) => {
    fileTreeContainer.classList.remove("hidden");
    fileTree.innerHTML = "<em>Loading repository file tree...</em>";
    const token = localStorage.getItem(GITHUB_TOKEN_KEY);
    if (!token || !repoFullName || !branch) return;

    try {
      const response = await fetch(
        `/api/github/tree?repo_full_name=${repoFullName}&branch=${branch}`,
        {
          headers: { Authorization: `Bearer ${token}` },
        }
      );
      if (!response.ok)
        throw new Error(
          `Failed to fetch file tree (status: ${response.status})`
        );
      const treeData = await response.json();
      fileTree.innerHTML = createTreeHtml(treeData);
    } catch (error) {
      console.error(error);
      fileTree.innerHTML = `<em style="color: #ef4444;">${error.message}</em>`;
    }
  };

// --- In script.js ---

  const switchMode = (mode) => {
    fileTreeContainer.classList.add("hidden");
    if (mode === "github") {
      selectGithubBtn.classList.add("active");
      selectZipBtn.classList.remove("active");
      githubInputs.classList.remove("hidden");
      zipInputs.classList.add("hidden");
      // GitHub Mode: ZIP is not required, GitHub fields are.
      zipFileInput.required = false;
      repoSelect.required = true;
      baseBranchSelect.required = true;
      newBranchInput.required = true;
      if (repoSelect.value)
        fetchAndBuildTree(repoSelect.value, baseBranchSelect.value);
    } else { // This is ZIP mode
      selectZipBtn.classList.add("active");
      selectGithubBtn.classList.remove("active");
      zipInputs.classList.remove("hidden");
      githubInputs.classList.add("hidden");
      // ZIP Mode: ZIP is required, GitHub fields are not.
      zipFileInput.required = true;
      repoSelect.required = false;
      baseBranchSelect.required = false; // <-- FIX: Added this line
      newBranchInput.required = false;   // <-- FIX: Added this line
    }
  };

  const handleFormSubmit = (e) => {
    e.preventDefault();
    resetProgressView();
    showView("live-progress-view");
    submitBtn.disabled = true;

    const formData = new FormData(docForm);
    const endpoint = selectGithubBtn.classList.contains("active")
      ? "/process-github"
      : "/process-zip";

    const headers = new Headers();
    if (endpoint === "/process-github") {
      headers.append(
        "Authorization",
        `Bearer ${localStorage.getItem(GITHUB_TOKEN_KEY)}`
      );
    }

    const options = { method: "POST", body: formData, headers: headers };

    fetch(endpoint, options)
      .then((response) => {
        if (!response.ok) {
          return response.json().then((errData) => {
            throw new Error(
              `Server error: ${response.status} - ${
                errData.detail || "Unknown error"
              }`
            );
          });
        }
        const reader = response.body.getReader();
        const decoder = new TextDecoder();
        let buffer = "";

        function push() {
          reader
            .read()
            .then(({ done, value }) => {
              if (done) {
                if (buffer) {
                  try {
                    const json = JSON.parse(buffer);
                    handleStreamEvent(json.type, json.payload);
                  } catch (e) {
                    console.error(
                      "Error parsing final buffer chunk:",
                      buffer,
                      e
                    );
                  }
                }
                return;
              }
              buffer += decoder.decode(value, { stream: true });
              const lines = buffer.split("\n");
              buffer = lines.pop();
              for (const line of lines) {
                if (line.trim() === "") continue;
                try {
                  const json = JSON.parse(line);
                  handleStreamEvent(json.type, json.payload);
                } catch (e) {
                  console.error("Failed to parse JSON line:", line, e);
                }
              }
              push();
            })
            .catch((err) => {
              console.error("Stream reading error:", err);
              handleStreamEvent("error", `Stream error: ${err.message}`);
            });
        }
        push();
      })
      .catch((err) => handleStreamEvent("error", `${err.message}`));
  };

  const handleStreamEvent = (type, payload) => {
    switch (type) {
      case "phase": {
        const phaseEl = document.getElementById(`phase-${payload.id}`);
        if (phaseEl) phaseEl.dataset.status = payload.status;
        break;
      }
      case "subtask": {
        const subtaskId = sanitizeForId(payload.id);
        let subtaskEl = document.getElementById(subtaskId);
        const listEl = document.getElementById(payload.listId);
        if (!subtaskEl && listEl) {
          subtaskEl = document.createElement("li");
          subtaskEl.id = subtaskId;
          subtaskEl.textContent = payload.name;
          listEl.appendChild(subtaskEl);
        }
        if (subtaskEl) subtaskEl.dataset.status = payload.status;
        break;
      }
      case "log": {
        logOutput.textContent += payload.message.replace(/\\n/g, "\n") + "\n";
        logOutput.scrollTop = logOutput.scrollHeight;
        break;
      }
      case "error": {
        document
          .querySelectorAll('.phase-item[data-status="in-progress"]')
          .forEach((el) => (el.dataset.status = "error"));
        logOutput.textContent += `\n\n--- ERROR ---\n${payload}\n`;
        submitBtn.disabled = false;
        break;
      }
      case "done": {
        showView("result-section");
        resultLink.innerHTML = `<p>${payload.message}</p>`;
        if (payload.type === "zip") {
          resultLink.innerHTML += `<a href="/download/${payload.download_path}" class="button-link" download>Download ZIP</a>`;
        } else if (payload.url) {
          const linkText = payload.url.includes("/pull/new/")
            ? "Create Pull Request"
            : "View Repository";
          resultLink.innerHTML += `<a href="${payload.url}" target="_blank" rel="noopener noreferrer" class="button-link">${linkText}</a>`;
        }
        submitBtn.disabled = false;
        break;
      }
    }
  };

  // --- Events ---
  githubLoginBtn.addEventListener(
    "click",
    () => (window.location.href = "/login/github")
  );
  selectZipBtn.addEventListener("click", () => switchMode("zip"));
  selectGithubBtn.addEventListener("click", () => switchMode("github"));
  docForm.addEventListener("submit", handleFormSubmit);

  repoSelect.addEventListener("change", async (e) => {
    const selectedOption = e.target.options[e.target.selectedIndex];
    const repoFullName = selectedOption.value;
    const defaultBranch = selectedOption.dataset.defaultBranch || "";

    if (repoFullName) {
      await fetchRepoBranches(repoFullName, defaultBranch);
      fetchAndBuildTree(repoFullName, baseBranchSelect.value);
      checkBranchName();
    } else {
      baseBranchSelect.innerHTML = "";
      fileTreeContainer.classList.add("hidden");
    }
  });

  baseBranchSelect.addEventListener("change", () => {
    fetchAndBuildTree(repoSelect.value, baseBranchSelect.value);
  });

  newBranchInput.addEventListener("blur", checkBranchName);

  // Initialize
  handleAuth();

  // --- UI Enhancements: glow cursor on buttons ---
  document.querySelectorAll(".btn-glow").forEach((btn) => {
    btn.addEventListener("pointermove", (e) => {
      const rect = btn.getBoundingClientRect();
      const x = ((e.clientX - rect.left) / rect.width) * 100;
      const y = ((e.clientY - rect.top) / rect.height) * 100;
      btn.style.setProperty("--x", x + "%");
      btn.style.setProperty("--y", y + "%");
    });
  });

  // --- Ripple effect for buttons and links ---
  function addRipple(e) {
    const el = e.currentTarget;
    const rect = el.getBoundingClientRect();
    const circle = document.createElement("span");
    circle.className = "ripple";
    circle.style.left = `${e.clientX - rect.left}px`;
    circle.style.top = `${e.clientY - rect.top}px`;
    el.appendChild(circle);
    setTimeout(() => circle.remove(), 600);
  }
  document.querySelectorAll("button.btn, .button-link").forEach((el) => {
    el.addEventListener("click", addRipple);
  });

  // --- Subtle parallax tilt on hover for panels and phase items ---
  const tiltEls = document.querySelectorAll(
    ".panel, .phase-item, .terminal, .glass-card"
  );
  tiltEls.forEach((el) => {
    let enter = false;
    el.addEventListener("pointerenter", () => {
      enter = true;
    });
    el.addEventListener("pointerleave", () => {
      enter = false;
      el.style.transform = "";
    });
    el.addEventListener("pointermove", (e) => {
      if (!enter) return;
      const rect = el.getBoundingClientRect();
      const cx = rect.left + rect.width / 2;
      const cy = rect.top + rect.height / 2;
      const dx = (e.clientX - cx) / rect.width;
      const dy = (e.clientY - cy) / rect.height;
      const max = 6;
      el.style.transform = `rotateX(${(-dy * max).toFixed(2)}deg) rotateY(${(
        dx * max
      ).toFixed(2)}deg) translateZ(0)`;
    });
  });

  // --- Optional: lightweight animated background canvas (respects reduced motion) ---
  const prefersReduced = window.matchMedia(
    "(prefers-reduced-motion: reduce)"
  ).matches;
  const canvas = document.getElementById("bg-canvas");
  if (canvas && !prefersReduced) {
    const ctx = canvas.getContext("2d", { alpha: true });
    let w, h, dots;
    function resize() {
      w = canvas.width = window.innerWidth;
      h = canvas.height = window.innerHeight;
      dots = Array.from(
        { length: Math.min(90, Math.floor((w * h) / 60000)) },
        () => ({
          x: Math.random() * w,
          y: Math.random() * h,
          vx: (Math.random() - 0.5) * 0.4,
          vy: (Math.random() - 0.5) * 0.4,
        })
      );
    }
    function step() {
      ctx.clearRect(0, 0, w, h);
      ctx.fillStyle = "rgba(34, 211, 238, 0.6)";
      const threshold = 120;
      for (let i = 0; i < dots.length; i++) {
        const a = dots[i];
        a.x += a.vx;
        a.y += a.vy;
        if (a.x < 0 || a.x > w) a.vx *= -1;
        if (a.y < 0 || a.y > h) a.vy *= -1;
        ctx.beginPath();
        ctx.arc(a.x, a.y, 1.2, 0, Math.PI * 2);
        ctx.fill();
        for (let j = i + 1; j < dots.length; j++) {
          const b = dots[j];
          const dx = a.x - b.x,
            dy = a.y - b.y;
          const dist = Math.hypot(dx, dy);
          if (dist < threshold) {
            const alpha = (1 - dist / threshold) * 0.2;
            ctx.strokeStyle = `rgba(96,165,250,${alpha})`;
            ctx.beginPath();
            ctx.moveTo(a.x, a.y);
            ctx.lineTo(b.x, b.y);
            ctx.stroke();
          }
        }
      }
      requestAnimationFrame(step);
    }
    window.addEventListener("resize", resize);
    resize();
    step();
  }
});