playlist-extension/background.js

// Background script for the extension

browser.storage.local.get("playlists").then(function (data) {
  if (!data.playlists) {
    console.log("pre-populating playlists");
    browser.storage.local.set({
      playlists: {
        "listening-1": [],
        "listening-2": [],
        "listening-3": [],
        "watching-1": [],
        "watching-2": [],
      },
    });
  } else {
    console.log("no need to pre-populate playlists");
  }
});

browser.storage.local.get("history").then(function (data) {
  if (!data.history) {
    console.log("pre-populating history");
    browser.storage.local.set({
      history: {},
    });
  } else {
    console.log("no need to pre-populate history");
  }
});

// Create context menu items when the extension is installed
browser.runtime.onInstalled.addListener(() => {
  // Parent menu item
  browser.contextMenus.create({
    id: "my-playlist-menu",
    title: "Add to Playlist",
    contexts: ["link"],
    targetUrlPatterns: ["https://*.youtube.com/watch*"],
  });

  // Sub-menu items
  browser.contextMenus.create({
    id: "listening-1",
    parentId: "my-playlist-menu",
    title: "Listening - 1",
    contexts: ["link"],
  });

  browser.contextMenus.create({
    id: "listening-2",
    parentId: "my-playlist-menu",
    title: "Listening - 2",
    contexts: ["link"],
  });

  browser.contextMenus.create({
    id: "listening-3",
    parentId: "my-playlist-menu",
    title: "Listening - 3",
    contexts: ["link"],
  });

  // Separator
  browser.contextMenus.create({
    id: "separator-1",
    parentId: "my-playlist-menu",
    type: "separator",
    contexts: ["link"],
  });

  browser.contextMenus.create({
    id: "watching-1",
    parentId: "my-playlist-menu",
    title: "Watching - 1",
    contexts: ["link"],
  });

  browser.contextMenus.create({
    id: "watching-2",
    parentId: "my-playlist-menu",
    title: "Watching - 2",
    contexts: ["link"],
  });
});

function findVideoInPlaylists(playlists, url) {
  // Extract the video id from URL query params
  let v;
  try {
    const urlObj = new URL(url);
    v = urlObj.searchParams.get("v");
  } catch (e) {
    return false; // Invalid URL
  }

  // If no video id found, return false
  if (!v) {
    return false;
  }

  // Check each playlist in the current set
  for (const playlistName in playlists) {
    const videos = playlists[playlistName];

    // Check each video in the array
    for (let i = 0; i < videos.length; i++) {
      try {
        const itemUrl = new URL(videos[i].url);
        const itemVParam = itemUrl.searchParams.get("v");

        // If the "v" parameters match, return playlist info
        if (itemVParam === v) {
          const isLastVideo = i === videos.length - 1;
          return [playlistName, i, isLastVideo];
        }
      } catch (e) {
        // Skip malformed URLs
        continue;
      }
    }
  }

  // No match found
  return false;
}

function findPlaylist(current, url) {
  const result = findVideoInPlaylists(current, url);
  // If found, return just the playlist name
  return result ? result[0] : false;
}

async function addLinkToPlaylist(plName, item) {
  const { playlists: currentPlaylists } =
    await browser.storage.local.get("playlists");

  const alreadyHave = findPlaylist(currentPlaylists, item.linkUrl);

  if (alreadyHave) {
    console.log("already have that link in", alreadyHave);
  } else {
    const { [plName]: playlist, ...others } = currentPlaylists;
    await browser.storage.local.set({
      playlists: {
        [plName]: [...playlist, { url: item.linkUrl, title: item.linkText }],
        ...others,
      },
    });
  }
}

// Context menu click handler
browser.contextMenus.onClicked.addListener(async (item, _tab) => {
  addLinkToPlaylist(item.menuItemId, item);
});

// Function to navigate a tab to a new URL
function navigateTab(tabId, url) {
  return browser.tabs.update(tabId, { url: url });
}

async function updateHistory(message) {
  const { history: currentHistory } =
    await browser.storage.local.get("history");
  const q = new URL(message.url);
  const v = q.searchParams.get("v");
  if (currentHistory[v]) {
    const { [v]: existing, ...rest } = currentHistory;

    const shouldIgnore =
      message.type === "playing" &&
      existing?.history?.length > 0 &&
      (existing.history[existing.history.length - 1].action === "play" ||
        existing.history[existing.history.length - 1].action === "playing") &&
      message.timestamp ===
        existing.history[existing.history.length - 1].position;

    if (!shouldIgnore) {
      await browser.storage.local.set({
        history: {
          [v]: {
            ...existing,
            duration:
              !isNaN(existing.duration) && isFinite(existing.duration)
                ? Math.max(message.duration, existing.duration)
                : message.duration,
            history: [
              ...existing.history,
              {
                action: message.type,
                position: message.timestamp,
                timestamp: Date.now(),
              },
            ],
          },
          ...rest,
        },
      });
    }
  } else {
    await browser.storage.local.set({
      history: {
        [v]: {
          url: message.url,
          title: message.title,
          duration: message.duration,
          history: [
            {
              action: message.type,
              position: message.timestamp,
              timestamp: Date.now(),
            },
          ],
        },
        ...currentHistory,
      },
    });
  }
}

function findNext(playlists, url) {
  const result = findVideoInPlaylists(playlists, url);

  if (!result) {
    return false; // Not found in any playlist
  }

  const [playlistName, videoIndex, isLastVideo] = result;

  if (isLastVideo) {
    return false; // Last video, no next video available
  } else {
    // Get next video in the playlist
    const nextVideo = playlists[playlistName][videoIndex + 1];
    console.log("FOUND VIDEO", playlists[playlistName][videoIndex]);
    return nextVideo;
  }
}

async function navigateAndWait(tabId, url) {
  return new Promise((resolve) => {
    const listener = (details) => {
      if (details.tabId === tabId && details.frameId === 0) {
        browser.webNavigation.onCompleted.removeListener(listener);
        setTimeout(resolve, 500);
      }
    };

    browser.webNavigation.onCompleted.addListener(listener);
    browser.tabs.update(tabId, { url });
  });
}

async function advance(tabId, url) {
  const { playlists } = await browser.storage.local.get("playlists");
  const nextVideo = await findNext(playlists, url);
  if (nextVideo) {
    await navigateAndWait(tabId, nextVideo.url);
    await browser.tabs.sendMessage(tabId, { type: "autoplay" });
  }
}

// Listen for messages from popup or content scripts
browser.runtime.onMessage.addListener((message, sender, _sendResponse) => {
  console.log("MESSAGE", message, sender);
  switch (message.type) {
    case "play":
    case "playing":
    case "pause":
      updateHistory(message);
      break;
    case "ended":
      updateHistory(message);
      advance(sender.tab.id, message.url);
      break;
  }
});