const ApiBase = "/api";

async function ParseJsonOrThrow(Response) {
  const Body = await Response.json().catch(() => null);

  if (!Response.ok) {
    const Detail = Body && Body.detail ? Body.detail : Response.statusText;
    throw new Error(Detail);
  }

  return Body;
}

function FetchJson(Path, Options = {}) {
  return fetch(`${ApiBase}${Path}`, { credentials: "same-origin", ...Options }).then(
    ParseJsonOrThrow
  );
}

function FetchText(Path, Options = {}) {
  return fetch(`${ApiBase}${Path}`, { credentials: "same-origin", ...Options }).then(
    (Response) => Response.text()
  );
}

function JsonBody(Body) {
  return { headers: { "Content-Type": "application/json" }, body: JSON.stringify(Body) };
}

export function FetchAuthStatus() {
  return FetchJson("/auth/status");
}

export function Bootstrap(Username, Password) {
  return FetchJson("/auth/bootstrap", { method: "POST", ...JsonBody({ Username, Password }) });
}

export function Login(Username, Password) {
  return FetchJson("/auth/login", { method: "POST", ...JsonBody({ Username, Password }) });
}

export function Logout() {
  return FetchJson("/auth/logout", { method: "POST" });
}

export function FetchMe() {
  return FetchJson("/auth/me");
}

export function FetchUsers() {
  return FetchJson("/users");
}

export function CreateUserAccount(Username, Password, IsAdmin, Colour) {
  return FetchJson("/users", { method: "POST", ...JsonBody({ Username, Password, IsAdmin, Colour }) });
}

export function FetchProfileColourOptions() {
  return FetchJson("/profile/colours");
}

export function UpdateProfileColour(Colour) {
  return FetchJson("/profile/colour", { method: "PUT", ...JsonBody({ Colour }) });
}

export async function UploadAvatar(File) {
  const Form = new FormData();
  Form.append("Avatar", File);
  const Response = await fetch(`${ApiBase}/profile/avatar`, {
    method: "POST",
    credentials: "same-origin",
    body: Form,
  });
  return ParseJsonOrThrow(Response);
}

export function GetAvatarUrl(Username) {
  const Params = new URLSearchParams({ Username });
  return `${ApiBase}/profile/avatar?${Params}`;
}

export function UpdateUsername(NewUsername) {
  return FetchJson("/profile/username", { method: "PUT", ...JsonBody({ NewUsername }) });
}

export function ChangePassword(CurrentPassword, NewPassword) {
  return FetchJson("/profile/password", {
    method: "PUT",
    ...JsonBody({ CurrentPassword, NewPassword }),
  });
}

export function FetchGroups() {
  return FetchJson("/groups");
}

export function CreateGroupApi(Name) {
  return FetchJson("/groups", { method: "POST", ...JsonBody({ Name }) });
}

export function DeleteGroupApi(Name) {
  const Params = new URLSearchParams({ Name });
  return FetchJson(`/groups?${Params}`, { method: "DELETE" });
}

export function SetGroupMembersApi(Name, Members) {
  const Params = new URLSearchParams({ Name });
  return FetchJson(`/groups/members?${Params}`, { method: "PUT", ...JsonBody({ Members }) });
}

export function FetchLocks() {
  return FetchJson("/locks");
}

export function FetchLock(RootName, RelativePath) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchJson(`/lock?${Params}`);
}

export function FetchInheritedLock(RootName, RelativePath) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchJson(`/lock/inherited?${Params}`);
}

export function SetLock(RootName, RelativePath, Users, Groups) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchJson(`/lock?${Params}`, { method: "PUT", ...JsonBody({ Users, Groups }) });
}

export function RemoveLock(RootName, RelativePath) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchJson(`/lock?${Params}`, { method: "DELETE" });
}

export function FetchRoots() {
  return FetchJson("/roots");
}

export function FetchTree(RootName, RelativePath) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchJson(`/tree?${Params}`);
}

export function FetchGraph(RootName, RelativePath) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchJson(`/graph?${Params}`);
}

export function FetchFile(RootName, RelativePath) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchText(`/file?${Params}`);
}

export function FetchResolvedFile(RootName, RelativePath) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchJson(`/file/resolved?${Params}`);
}

export function GetFileUrl(RootName, RelativePath) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return `${ApiBase}/file?${Params}`;
}

export function GetRawFileUrl(RootName, RelativePath) {
  const EncodedSegments = RelativePath.split("/").map(encodeURIComponent);
  return `${ApiBase}/raw/${encodeURIComponent(RootName)}/${EncodedSegments.join("/")}`;
}

export function GetDownloadUrl(RootName, RelativePath) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return `${ApiBase}/download?${Params}`;
}

// Uploads go through XMLHttpRequest: unlike fetch, it reports how much has
// been sent. OnProgress(BytesSent) is optional.
function PostFormWithProgress(Url, Form, OnProgress) {
  return new Promise((Resolve, Reject) => {
    const Request = new XMLHttpRequest();
    Request.open("POST", Url);
    Request.withCredentials = true;
    if (OnProgress) {
      Request.upload.onprogress = (Event) => OnProgress(Event.loaded);
    }
    Request.onload = () => {
      let Body = null;
      try {
        Body = JSON.parse(Request.responseText);
      } catch {
        Body = null;
      }
      if (Request.status >= 200 && Request.status < 300) {
        Resolve(Body);
      } else {
        Reject(new Error(Body && Body.detail ? Body.detail : Request.statusText || `Upload failed (${Request.status})`));
      }
    };
    Request.onerror = () => Reject(new Error("Upload failed: couldn't reach the server."));
    Request.send(Form);
  });
}

export function UploadFiles(RootName, RelativePath, Files, OnProgress) {
  const Form = new FormData();
  for (const File of Files) {
    Form.append("Files", File);
  }
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return PostFormWithProgress(`${ApiBase}/upload?${Params}`, Form, OnProgress);
}

const UploadChunkSizeBytes = 20 * 1024 * 1024;
export const ChunkedUploadThresholdBytes = 40 * 1024 * 1024;

export function IsLargeUpload(File) {
  return File.size > ChunkedUploadThresholdBytes;
}

function GenerateUploadId() {
  if (window.crypto && window.crypto.randomUUID) {
    return window.crypto.randomUUID();
  }
  return `${Date.now()}-${Math.random().toString(16).slice(2)}`;
}

function UploadFileChunk(RootName, RelativePath, UploadId, ChunkIndex, TotalChunks, FileName, ChunkBlob, OnProgress) {
  const Form = new FormData();
  Form.append("Chunk", ChunkBlob, "chunk");
  const Params = new URLSearchParams({
    Root: RootName,
    Path: RelativePath,
    UploadId,
    ChunkIndex: String(ChunkIndex),
    TotalChunks: String(TotalChunks),
    FileName,
  });
  return PostFormWithProgress(`${ApiBase}/upload/chunk?${Params}`, Form, OnProgress);
}

function CompleteChunkedUpload(RootName, RelativePath, UploadId, TotalChunks, FileName) {
  const Params = new URLSearchParams({
    Root: RootName,
    Path: RelativePath,
    UploadId,
    TotalChunks: String(TotalChunks),
    FileName,
  });
  return FetchJson(`/upload/complete?${Params}`, { method: "POST" });
}

// OnProgress(BytesSent) counts across all the chunks.
export async function UploadFileChunked(RootName, RelativePath, File, OnProgress) {
  const UploadId = GenerateUploadId();
  const TotalChunks = Math.max(1, Math.ceil(File.size / UploadChunkSizeBytes));

  for (let ChunkIndex = 0; ChunkIndex < TotalChunks; ChunkIndex++) {
    const Start = ChunkIndex * UploadChunkSizeBytes;
    const ChunkBlob = File.slice(Start, Start + UploadChunkSizeBytes);
    await UploadFileChunk(RootName, RelativePath, UploadId, ChunkIndex, TotalChunks, File.name, ChunkBlob,
      OnProgress && ((Sent) => OnProgress(Start + Math.min(Sent, ChunkBlob.size))));
  }

  return CompleteChunkedUpload(RootName, RelativePath, UploadId, TotalChunks, File.name);
}

// Where each variable (portal, definition, loop) is in Content, and what it
// resolves to: the live editor shows the results in place (LivePreview.js).
export function FetchSpans(RootName, RelativePath, Content) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchJson(`/file/spans?${Params}`, { method: "POST", ...JsonBody({ Content }) });
}

export function SaveFile(RootName, RelativePath, Content) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchJson(`/file?${Params}`, { method: "PUT", body: Content });
}

export function FetchBook(RootName, RelativePath) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchJson(`/book?${Params}`);
}

export function FetchBlame(RootName, RelativePath) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchJson(`/blame?${Params}`);
}

export function CreateEntry(RootName, RelativePath, IsDirectory) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchJson(`/tree?${Params}`, { method: "POST", ...JsonBody({ IsDirectory }) });
}

export function RenameEntry(RootName, RelativePath, NewName) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchJson(`/tree?${Params}`, { method: "PATCH", ...JsonBody({ NewName }) });
}

export function MoveEntry(RootName, RelativePath, DestinationPath) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchJson(`/tree?${Params}`, { method: "PATCH", ...JsonBody({ DestinationPath }) });
}

export function DeleteEntry(RootName, RelativePath) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchJson(`/tree?${Params}`, { method: "DELETE" });
}

export function EnsureDirectoryNote(RootName, RelativePath) {
  const Params = new URLSearchParams({ Root: RootName, Path: RelativePath });
  return FetchJson(`/note?${Params}`, { method: "POST" });
}

export function FetchSettings() {
  return FetchJson("/settings");
}

export function SaveSettings(NewSettings) {
  return FetchJson("/settings", { method: "PUT", ...JsonBody(NewSettings) });
}

export function FetchThemeNames() {
  return FetchJson("/themes");
}

export function FetchTheme(Name) {
  const Params = new URLSearchParams({ Name });
  return FetchJson(`/theme?${Params}`);
}

export function SaveTheme(Name, Palette) {
  const Params = new URLSearchParams({ Name });
  return FetchJson(`/theme?${Params}`, { method: "PUT", ...JsonBody({ Palette }) });
}

export function DeleteTheme(Name) {
  const Params = new URLSearchParams({ Name });
  return FetchJson(`/theme?${Params}`, { method: "DELETE" });
}