/**
 * Build the filetree
 * @param {HTMLElement} parent Root element of the filetree
 * @param {{name: string, is_dir: boolean, children: any[]}} data FileNode
 * @param {string} location Current location, used for links creation
 */
const buildFileTree = (parent, data, location) => {
  const ul = document.createElement("ul");
  data.forEach((item) => {
    const li = document.createElement("li");
    li.classList.add(item.is_dir ? "directory" : "file");

    if (item.is_dir) {
      // Directory
      li.textContent = item.name;
      li.classList.add("collapsed");

      // Toggle collapsing on click
      li.addEventListener("click", function (e) {
        if (e.target === li) {
          li.classList.toggle("collapsed");
        }
      });
    } else {
      // File
      const url = window.location.href.split("?")[0];
      const a = document.createElement("a");
      a.text = item.name;
      a.href = `${url}?q=${location}${item.name}`;
      li.appendChild(a);
    }

    ul.appendChild(li);

    if (item.children && item.children.length > 0) {
      buildFileTree(
        li,
        item.children,
        item.is_dir ? location + `${item.name}/` : location
      );
    }
  });

  parent.appendChild(ul);
};

/**
 * Uncollapse elements from the deepest element
 * @param {HTMLLIElement} element Element to uncollapse
 */
const uncollapse = (element) => {
  if (element) {
    element.classList.remove("collapsed");
    uncollapse(element.parentElement.closest("li"));
  }
};

/**
 * Find the deepest opened directory
 * @param {string[]} path Current path we are looking at, init with fullpath
 * @param {NodeListOf<ChildNode>} options Options we have, init with list root
 * @returns
 */
const deepestNodeOpened = (path, options) => {
  // Iterate over possible options
  for (let i = 0; i < options.length; ++i) {
    // If the directory and the current path match
    if (decodeURI(path[0]) === options[i].firstChild.nodeValue) {
      if (path.length === 1) {
        // We found it
        return options[i];
      }

      // Continue the search
      return deepestNodeOpened(
        path.slice(1),
        options[i].querySelector("ul").childNodes
      );
    }
  }
};

const svgDarkTheme = () => {
  for (const item of document.getElementsByTagName("img")) {
    if (!item.src.startsWith("data:image/svg+xml;base64,")) {
      // Exclude image who aren't SVG and base64 encoded
      break;
    }

    /** Convert to grayscale */
    const colorToGrayscale = (color) => {
      return 0.3 * color.r + 0.59 * color.g + 0.11 * color.b;
    };

    /** Extract color using canvas2d */
    const extractColors = (image) => {
      const canvas = document.createElement("canvas");
      canvas.width = image.width;
      canvas.height = image.height;
      const ctx = canvas.getContext("2d");
      ctx.drawImage(image, 0, 0);
      const imageData = ctx.getImageData(
        0,
        0,
        Math.max(1, canvas.width),
        Math.max(1, canvas.height)
      );
      const pixelData = imageData.data;

      const colors = [];
      for (let i = 0; i < pixelData.length; i += 4) {
        if (pixelData[i + 3] > 0) {
          colors.push({
            r: pixelData[i],
            g: pixelData[i + 1],
            b: pixelData[i + 2],
          });
        }
      }

      return colors;
    };

    // Extract colors
    const colors = extractColors(item);

    // Calculate the average grayscale value
    const grayscaleValues = colors.map(colorToGrayscale);
    const totalGrayscale = grayscaleValues.reduce((acc, val) => acc + val, 0);
    const averageGrayscale = totalGrayscale / grayscaleValues.length;

    if (averageGrayscale < 128) {
      item.style = "filter: invert(1);";
    }
  }
};

window.addEventListener("load", () => {
  // Build the filetree
  const fileTreeElement = document.getElementsByTagName("aside")[0];
  const dataElement = fileTreeElement.getElementsByTagName("span")[0];

  buildFileTree(
    fileTreeElement,
    JSON.parse(dataElement.getAttribute("data-json")).children,
    ""
  );
  dataElement.remove();

  // Open nested openeded directories
  const infoURL = window.location.href.split("?");
  if (infoURL.length > 1) {
    const fullpath = infoURL[1].substring(2);
    const path = fullpath.substring(0, fullpath.lastIndexOf("/"));
    const last_openeded = deepestNodeOpened(
      path.split("/"),
      fileTreeElement.querySelector("ul").childNodes
    );

    uncollapse(last_openeded);
  }

  // Fix SVG images in dark mode
  if (window.matchMedia("(prefers-color-scheme: dark)").matches) {
    svgDarkTheme();
  }
});