import React, { useEffect, useState } from "react";

import Sidebar from "./Components/Sidebar.jsx";
import Breadcrumb from "./Components/Breadcrumb.jsx";
import PreviewPane from "./Components/PreviewPane.jsx";
import DirectoryPane from "./Components/DirectoryPane.jsx";
import TagPanel from "./Components/TagPanel.jsx";
import SettingsPanel from "./Components/SettingsPanel.jsx";
import GraphPane from "./Components/GraphPane.jsx";
import LoginScreen from "./Components/LoginScreen.jsx";
import ErrorToast from "./Components/ErrorToast.jsx";
import {
  EnsureDirectoryNote,
  FetchAuthStatus,
  FetchMe,
  FetchRoots,
  FetchSettings,
  FetchTheme,
  FetchTree,
} from "./Api.js";
import { PaletteRoles } from "./ThemeRoles.js";

function ApplyTheme(Palette) {
  const RootStyle = document.documentElement.style;
  PaletteRoles.forEach((Role) => {
    if (Palette[Role]) {
      RootStyle.setProperty(`--${Role}`, Palette[Role]);
    }
  });
}

function ApplyFont(Settings) {
  const RootStyle = document.documentElement.style;
  RootStyle.setProperty(
    "--FontFamily",
    `"${Settings.FontFamily}", "Cascadia Mono", monospace`
  );
  RootStyle.setProperty("--FontSize", `${Settings.FontSize}px`);
}

function GetParentPath(FilePath) {
  return FilePath.includes("/") ? FilePath.slice(0, FilePath.lastIndexOf("/")) : "";
}

function BuildLocationPath(RootName, ViewPath, ViewIsDirectory) {
  const Segments = [RootName, ...ViewPath.split("/").filter(Boolean)];
  const Encoded = "/" + Segments.map(encodeURIComponent).join("/");
  return ViewIsDirectory ? `${Encoded}/` : Encoded;
}

function ParseLocationPath(Pathname) {
  const IsDirectory = Pathname.endsWith("/");
  const Segments = Pathname.split("/").filter(Boolean).map(decodeURIComponent);
  const [RootName, ...RestSegments] = Segments;
  return { RootName: RootName || null, Path: RestSegments.join("/"), IsDirectory };
}

const GuestUser = { Username: null, IsAdmin: false, IsGuest: true, Colour: "Purple" };

export default function App() {
  const [AuthState, SetAuthState] = useState("Loading");
  const [CurrentUser, SetCurrentUser] = useState(null);

  const [Roots, SetRoots] = useState([]);
  const [ActiveRoot, SetActiveRoot] = useState(null);
  const [ViewPath, SetViewPath] = useState("");
  const [ViewIsDirectory, SetViewIsDirectory] = useState(true);
  const [ViewFileType, SetViewFileType] = useState(null);
  const [ViewNoteFilePath, SetViewNoteFilePath] = useState(null);
  const [CurrentDirectoryPath, SetCurrentDirectoryPath] = useState("");
  const [SidebarKey, SetSidebarKey] = useState(0);
  const [Settings, SetSettings] = useState(null);
  const [IsSettingsOpen, SetIsSettingsOpen] = useState(false);
  const [IsGraphOpen, SetIsGraphOpen] = useState(false);
  const [ErrorMessage, SetErrorMessage] = useState(null);

  useEffect(() => {
    FetchAuthStatus().then((Status) => {
      if (!Status.SetupComplete) {
        SetAuthState("Bootstrap");
        return;
      }

      FetchMe()
        .then((User) => {
          SetCurrentUser(User);
          SetAuthState("LoggedIn");
        })
        .catch(() => {
          SetCurrentUser(GuestUser);
          SetAuthState("Guest");
        });
    });
  }, []);

  const IsUsable = AuthState === "LoggedIn" || AuthState === "Guest";

  useEffect(() => {
    if (!IsUsable) return;

    FetchRoots().then((Fetched) => {
      SetRoots(Fetched);
      RestoreFromLocation(Fetched);
    });

    FetchSettings().then((FetchedSettings) => {
      SetSettings(FetchedSettings);
      ApplyFont(FetchedSettings);
      FetchTheme(FetchedSettings.ThemeName).then(ApplyTheme);
    });
  }, [AuthState]);

  useEffect(() => {
    if (!IsUsable || !ActiveRoot) return;

    const Url = BuildLocationPath(ActiveRoot, ViewPath, ViewIsDirectory);
    if (window.location.pathname !== Url) {
      window.history.pushState({}, "", Url);
    }
  }, [AuthState, ActiveRoot, ViewPath, ViewIsDirectory]);

  useEffect(() => {
    if (!IsUsable) return;

    function HandlePopState() {
      RestoreFromLocation(Roots);
    }

    window.addEventListener("popstate", HandlePopState);
    return () => window.removeEventListener("popstate", HandlePopState);
  }, [AuthState, Roots]);

  async function RestoreFromLocation(RootsList) {
    const { RootName, Path, IsDirectory } = ParseLocationPath(window.location.pathname);
    const MatchedRoot = RootsList.find((Root) => Root.Name === RootName);

    if (!MatchedRoot) {
      if (RootsList.length > 0) {
        SetActiveRoot(RootsList[0].Name);
      }
      return;
    }

    SetActiveRoot(RootName);

    if (!Path) {
      HandleNavigateDirectory("");
      return;
    }

    const LastSlash = Path.lastIndexOf("/");
    const ParentPath = LastSlash === -1 ? "" : Path.slice(0, LastSlash);
    const EntryName = LastSlash === -1 ? Path : Path.slice(LastSlash + 1);

    try {
      const Entries = await FetchTree(RootName, ParentPath);
      const Entry = Entries.find((Candidate) => Candidate.Name === EntryName);

      if (!Entry) {
        HandleNavigateDirectory("");
        return;
      }

      if (Entry.IsDirectory) {
        if (IsDirectory) {
          HandleNavigateDirectory(Path);
        } else {
          OpenDirectoryNote(Path, Entry.Note);
        }
      } else {
        HandleSelectFile(Path, Entry.FileType);
      }
    } catch (Error) {
      HandleNavigateDirectory("");
    }
  }

  function HandleAuthenticated(User) {
    SetCurrentUser(User);
    SetAuthState("LoggedIn");
  }

  function HandleLoggedOut() {
    SetCurrentUser(null);
    SetAuthState("LoggedOut");
  }

  function HandleContinueAsGuest() {
    SetCurrentUser(GuestUser);
    SetAuthState("Guest");
  }

  function HandleRequestLogin() {
    SetCurrentUser(null);
    SetAuthState("LoggedOut");
  }

  function HandleProfileUpdated(UpdatedUser) {
    SetCurrentUser((Existing) => ({ ...Existing, ...UpdatedUser }));
  }

  function HandleSettingsChanged(NewSettings) {
    SetSettings(NewSettings);
    ApplyFont(NewSettings);
    FetchTheme(NewSettings.ThemeName).then(ApplyTheme);
    SetSidebarKey((Key) => Key + 1);
  }

  function HandleSelectFile(FilePath, FileType) {
    SetViewPath(FilePath);
    SetViewIsDirectory(false);
    SetViewFileType(FileType);
    SetViewNoteFilePath(null);
    SetCurrentDirectoryPath(GetParentPath(FilePath));
  }

  function HandleNavigateDirectory(DirectoryPath) {
    SetViewPath(DirectoryPath);
    SetViewIsDirectory(true);
    SetViewFileType(null);
    SetViewNoteFilePath(null);
    SetCurrentDirectoryPath(DirectoryPath);
  }

  function HandleBrowseDirectory(DirectoryPath) {
    SetCurrentDirectoryPath(DirectoryPath);
  }

  function HandleSelectDirectoryNote(DirectoryPath, NoteName, NoteFileType) {
    SetViewPath(DirectoryPath);
    SetViewIsDirectory(false);
    SetViewFileType(NoteFileType);
    SetViewNoteFilePath(`${DirectoryPath}/${NoteName}`);
    SetCurrentDirectoryPath(DirectoryPath);
  }

  async function OpenDirectoryNote(DirectoryPath, Note) {
    if (Note) {
      HandleSelectDirectoryNote(DirectoryPath, Note.Name, Note.FileType);
      return;
    }

    try {
      const Created = await EnsureDirectoryNote(ActiveRoot, DirectoryPath);
      HandleSelectDirectoryNote(DirectoryPath, Created.Name, Created.FileType);
    } catch (Error) {
      HandleNavigateDirectory(DirectoryPath);
    }
  }

  function HandleBreadcrumbNavigate(Path) {
    if (!Path) {
      HandleNavigateDirectory("");
    } else {
      OpenDirectoryNote(Path, null);
    }
  }

  function HandleOpenGraphNode(Node) {
    SetIsGraphOpen(false);
    if (Node.IsDirectory) {
      HandleBreadcrumbNavigate(Node.Id);
    } else {
      HandleSelectFile(Node.Id, Node.FileType);
    }
  }

  function HandleEntrySelect(EntryPath, IsDirectory, FileType, Note) {
    if (IsDirectory) {
      OpenDirectoryNote(EntryPath, Note);
    } else {
      HandleSelectFile(EntryPath, FileType);
    }
  }

  function RefreshSidebar() {
    SetSidebarKey((Key) => Key + 1);
  }

  function HandleEntryRenamed(OldPath, NewPath, IsDirectory) {
    RefreshSidebar();

    if (ViewNoteFilePath && ViewPath === OldPath) {
      OpenDirectoryNote(NewPath, null);
    } else if (!ViewIsDirectory && ViewPath === OldPath) {
      HandleSelectFile(NewPath, ViewFileType);
    } else if (ViewIsDirectory && ViewPath === OldPath) {
      HandleNavigateDirectory(NewPath);
    } else if (CurrentDirectoryPath === OldPath) {
      SetCurrentDirectoryPath(NewPath);
    }
  }

  function HandleEntryDeleted(DeletedPath) {
    RefreshSidebar();

    if (ViewPath === DeletedPath || ViewPath.startsWith(`${DeletedPath}/`)) {
      HandleNavigateDirectory(GetParentPath(DeletedPath));
    } else if (CurrentDirectoryPath === DeletedPath || CurrentDirectoryPath.startsWith(`${DeletedPath}/`)) {
      SetCurrentDirectoryPath(GetParentPath(DeletedPath));
    }
  }

  if (AuthState === "Loading") {
    return null;
  }

  if (AuthState === "Bootstrap") {
    return <LoginScreen IsBootstrap OnAuthenticated={HandleAuthenticated} />;
  }

  if (AuthState === "LoggedOut") {
    return (
      <LoginScreen
        IsBootstrap={false}
        OnAuthenticated={HandleAuthenticated}
        OnContinueAsGuest={HandleContinueAsGuest}
      />
    );
  }

  const IsGuest = AuthState === "Guest";
  const ShowTopBar = (Settings && Settings.ShowBreadcrumbs) || Roots.length > 1;
  const ConfirmBeforeDelete = Settings ? Settings.ConfirmBeforeDelete : true;

  return (
    <div className="AppShell">
      <Sidebar
        key={SidebarKey}
        RootName={ActiveRoot}
        SelectedFile={ViewIsDirectory ? null : ViewPath}
        CurrentDirectoryPath={CurrentDirectoryPath}
        CurrentUser={CurrentUser}
        IsGuest={IsGuest}
        OnSelectFile={HandleSelectFile}
        OnSelectDirectory={OpenDirectoryNote}
        OnNavigateDirectory={HandleNavigateDirectory}
        OnBrowseDirectory={HandleBrowseDirectory}
        OnEntryRenamed={HandleEntryRenamed}
        OnEntryDeleted={HandleEntryDeleted}
        OnOpenSettings={() => SetIsSettingsOpen(true)}
        OnToggleGraph={() => SetIsGraphOpen(!IsGraphOpen)}
        IsGraphOpen={IsGraphOpen}
        OnRequestLogin={HandleRequestLogin}
        OnEntryCreated={RefreshSidebar}
        UseHyphenBullets={Settings ? Settings.UseHyphenBullets : true}
        UseAsciiFolderIcons={Settings ? Settings.UseAsciiFolderIcons : true}
        NavigateIntoDirectories={Settings ? Settings.NavigateIntoDirectories : false}
        NewEntryButtonsAtTop={Settings ? Settings.NewEntryButtonsAtTop : false}
        ConfirmBeforeDelete={ConfirmBeforeDelete}
      />
      <div className="MainColumn">
        {ShowTopBar && (
          <div className="TopBar">
            {Settings && Settings.ShowBreadcrumbs ? (
              <Breadcrumb
                RootName={ActiveRoot}
                FilePath={ViewPath}
                IsDirectory={ViewIsDirectory || Boolean(ViewNoteFilePath)}
                OnNavigate={HandleBreadcrumbNavigate}
              />
            ) : (
              <span />
            )}
            {Roots.length > 1 && (
              <select
                className="RootSwitcher"
                value={ActiveRoot || ""}
                onChange={(Event) => SetActiveRoot(Event.target.value)}
              >
                {Roots.map((Root) => (
                  <option key={Root.Name} value={Root.Name}>
                    {Root.Name}
                  </option>
                ))}
              </select>
            )}
          </div>
        )}
        <div className="MainBody">
          {IsGraphOpen ? (
            <GraphPane
              RootName={ActiveRoot}
              DirectoryPath={CurrentDirectoryPath}
              ShowDirectories={Settings ? Settings.GraphShowDirectories : true}
              PanButton={Settings ? Settings.GraphPanButton : "Right"}
              ColourByDepth={Settings ? Settings.GraphColourByDepth : true}
              ShrinkByDepth={Settings ? Settings.GraphShrinkByDepth : false}
              OnOpenNode={HandleOpenGraphNode}
              OnClose={() => SetIsGraphOpen(false)}
            />
          ) : ViewIsDirectory ? (
            <DirectoryPane
              RootName={ActiveRoot}
              DirectoryPath={ViewPath}
              OnEntrySelect={HandleEntrySelect}
              OnEntryCreated={RefreshSidebar}
              OnEntryRenamed={HandleEntryRenamed}
              OnEntryDeleted={HandleEntryDeleted}
              UseHyphenBullets={Settings ? Settings.UseHyphenBullets : true}
              UseAsciiFolderIcons={Settings ? Settings.UseAsciiFolderIcons : true}
              ConfirmBeforeDelete={ConfirmBeforeDelete}
              IsGuest={IsGuest}
            />
          ) : (
            <PreviewPane
              RootName={ActiveRoot}
              FilePath={ViewNoteFilePath || ViewPath}
              FileType={ViewFileType}
              OnNavigateLink={HandleSelectFile}
              ShowGitBlame={Settings ? Settings.ShowGitBlame : false}
              ShowBlameAvatars={Settings ? Settings.ShowBlameAvatars : false}
              StickyToolbar={Settings ? Settings.StickyToolbar : true}
              MarkdownEditing={Settings ? Settings.MarkdownEditing : "Live"}
              IsGuest={IsGuest}
            />
          )}
          {!IsGraphOpen && !ViewIsDirectory && !ViewNoteFilePath && (
            <TagPanel RootName={ActiveRoot} FilePath={ViewPath} />
          )}
        </div>
      </div>
      {IsSettingsOpen && (
        <SettingsPanel
          CurrentUser={CurrentUser}
          OnClose={() => SetIsSettingsOpen(false)}
          OnSettingsChanged={HandleSettingsChanged}
          OnLoggedOut={HandleLoggedOut}
          OnProfileUpdated={HandleProfileUpdated}
        />
      )}
      <ErrorToast Message={ErrorMessage} OnDismiss={() => SetErrorMessage(null)} />
    </div>
  );
}