import * as vscode from 'vscode';
import * as path from "path";
import * as os from "os";
import { promises as fs, PathLike } from "fs";

import * as commands from './commands';
import { activateInlayHints } from './inlay_hints';
import { Ctx } from './ctx';
import { Config, NIGHTLY_TAG } from './config';
import { log, assert, isValidExecutable } from './util';
import { PersistentState } from './persistent_state';
import { fetchRelease, download } from './net';
import { activateTaskProvider } from './tasks';
import { setContextValue } from './util';
import { exec } from 'child_process';

let ctx: Ctx | undefined;

const RUST_PROJECT_CONTEXT_NAME = "inRustProject";

export async function activate(context: vscode.ExtensionContext) {
    // For some reason vscode not always shows pop-up error notifications
    // when an extension fails to activate, so we do it explicitly by ourselves.
    // FIXME: remove this bit of code once vscode fixes this issue: https://github.com/microsoft/vscode/issues/101242
    await tryActivate(context).catch(err => {
        void vscode.window.showErrorMessage(`Cannot activate rust-analyzer: ${err.message}`);
        throw err;
    });
}

async function tryActivate(context: vscode.ExtensionContext) {
    // Register a "dumb" onEnter command for the case where server fails to
    // start.
    //
    // FIXME: refactor command registration code such that commands are
    // **always** registered, even if the server does not start. Use API like
    // this perhaps?
    //
    // ```TypeScript
    // registerCommand(
    //    factory: (Ctx) => ((Ctx) => any),
    //    fallback: () => any = () => vscode.window.showErrorMessage(
    //        "rust-analyzer is not available"
    //    ),
    // )
    const defaultOnEnter = vscode.commands.registerCommand(
        'rust-analyzer.onEnter',
        () => vscode.commands.executeCommand('default:type', { text: '\n' }),
    );
    context.subscriptions.push(defaultOnEnter);

    const config = new Config(context);
    const state = new PersistentState(context.globalState);
    const serverPath = await bootstrap(config, state).catch(err => {
        let message = "bootstrap error. ";

        if (err.code === "EBUSY" || err.code === "ETXTBSY" || err.code === "EPERM") {
            message += "Other vscode windows might be using rust-analyzer, ";
            message += "you should close them and reload this window to retry. ";
        }

        message += 'See the logs in "OUTPUT > Rust Analyzer Client" (should open automatically). ';
        message += 'To enable verbose logs use { "rust-analyzer.trace.extension": true }';

        log.error("Bootstrap error", err);
        throw new Error(message);
    });

    const workspaceFolder = vscode.workspace.workspaceFolders?.[0];
    if (workspaceFolder === undefined) {
        throw new Error("no folder is opened");
    }

    // Note: we try to start the server before we activate type hints so that it
    // registers its `onDidChangeDocument` handler before us.
    //
    // This a horribly, horribly wrong way to deal with this problem.
    ctx = await Ctx.create(config, context, serverPath, workspaceFolder.uri.fsPath);

    setContextValue(RUST_PROJECT_CONTEXT_NAME, true);

    // Commands which invokes manually via command palette, shortcut, etc.

    // Reloading is inspired by @DanTup maneuver: https://github.com/microsoft/vscode/issues/45774#issuecomment-373423895
    ctx.registerCommand('reload', _ => async () => {
        void vscode.window.showInformationMessage('Reloading rust-analyzer...');
        await deactivate();
        while (context.subscriptions.length > 0) {
            try {
                context.subscriptions.pop()!.dispose();
            } catch (err) {
                log.error("Dispose error:", err);
            }
        }
        await activate(context).catch(log.error);
    });

    ctx.registerCommand('updateGithubToken', ctx => async () => {
        await queryForGithubToken(new PersistentState(ctx.globalState));
    });

    ctx.registerCommand('analyzerStatus', commands.analyzerStatus);
    ctx.registerCommand('memoryUsage', commands.memoryUsage);
    ctx.registerCommand('reloadWorkspace', commands.reloadWorkspace);
    ctx.registerCommand('matchingBrace', commands.matchingBrace);
    ctx.registerCommand('joinLines', commands.joinLines);
    ctx.registerCommand('parentModule', commands.parentModule);
    ctx.registerCommand('syntaxTree', commands.syntaxTree);
    ctx.registerCommand('expandMacro', commands.expandMacro);
    ctx.registerCommand('run', commands.run);
    ctx.registerCommand('debug', commands.debug);
    ctx.registerCommand('newDebugConfig', commands.newDebugConfig);

    defaultOnEnter.dispose();
    ctx.registerCommand('onEnter', commands.onEnter);

    ctx.registerCommand('ssr', commands.ssr);
    ctx.registerCommand('serverVersion', commands.serverVersion);
    ctx.registerCommand('toggleInlayHints', commands.toggleInlayHints);

    // Internal commands which are invoked by the server.
    ctx.registerCommand('runSingle', commands.runSingle);
    ctx.registerCommand('debugSingle', commands.debugSingle);
    ctx.registerCommand('showReferences', commands.showReferences);
    ctx.registerCommand('applySnippetWorkspaceEdit', commands.applySnippetWorkspaceEditCommand);
    ctx.registerCommand('resolveCodeAction', commands.resolveCodeAction);
    ctx.registerCommand('applyActionGroup', commands.applyActionGroup);
    ctx.registerCommand('gotoLocation', commands.gotoLocation);

    ctx.pushCleanup(activateTaskProvider(workspaceFolder, ctx.config));

    activateInlayHints(ctx);

    vscode.workspace.onDidChangeConfiguration(
        _ => ctx?.client?.sendNotification('workspace/didChangeConfiguration', { settings: "" }),
        null,
        ctx.subscriptions,
    );
}

export async function deactivate() {
    setContextValue(RUST_PROJECT_CONTEXT_NAME, undefined);
    await ctx?.client.stop();
    ctx = undefined;
}

async function bootstrap(config: Config, state: PersistentState): Promise<string> {
    await fs.mkdir(config.globalStoragePath, { recursive: true });

    await bootstrapExtension(config, state);
    const path = await bootstrapServer(config, state);

    return path;
}

async function bootstrapExtension(config: Config, state: PersistentState): Promise<void> {
    if (config.package.releaseTag === null) return;
    if (config.channel === "stable") {
        if (config.package.releaseTag === NIGHTLY_TAG) {
            void vscode.window.showWarningMessage(
                `You are running a nightly version of rust-analyzer extension. ` +
                `To switch to stable, uninstall the extension and re-install it from the marketplace`
            );
        }
        return;
    };

    const now = Date.now();
    if (config.package.releaseTag === NIGHTLY_TAG) {
        // Check if we should poll github api for the new nightly version
        // if we haven't done it during the past hour
        const lastCheck = state.lastCheck;

        const anHour = 60 * 60 * 1000;
        const shouldCheckForNewNightly = state.releaseId === undefined || (now - (lastCheck ?? 0)) > anHour;

        if (!shouldCheckForNewNightly) return;
    }

    const release = await performDownloadWithRetryDialog(async () => {
        return await fetchRelease("nightly", state.githubToken);
    }, state).catch((e) => {
        log.error(e);
        if (state.releaseId === undefined) { // Show error only for the initial download
            vscode.window.showErrorMessage(`Failed to download rust-analyzer nightly ${e}`);
        }
        return undefined;
    });
    if (release === undefined || release.id === state.releaseId) return;

    const userResponse = await vscode.window.showInformationMessage(
        "New version of rust-analyzer (nightly) is available (requires reload).",
        "Update"
    );
    if (userResponse !== "Update") return;

    const artifact = release.assets.find(artifact => artifact.name === "rust-analyzer.vsix");
    assert(!!artifact, `Bad release: ${JSON.stringify(release)}`);

    const dest = path.join(config.globalStoragePath, "rust-analyzer.vsix");

    await performDownloadWithRetryDialog(async () => {
        // Unlinking the exe file before moving new one on its place should prevent ETXTBSY error.
        await fs.unlink(dest).catch(err => {
            if (err.code !== "ENOENT") throw err;
        });

        await download({
            url: artifact.browser_download_url,
            dest,
            progressTitle: "Downloading rust-analyzer extension",
        });
    }, state);

    await vscode.commands.executeCommand("workbench.extensions.installExtension", vscode.Uri.file(dest));
    await fs.unlink(dest);

    await state.updateReleaseId(release.id);
    await state.updateLastCheck(now);
    await vscode.commands.executeCommand("workbench.action.reloadWindow");
}

async function bootstrapServer(config: Config, state: PersistentState): Promise<string> {
    const path = await getServer(config, state);
    if (!path) {
        throw new Error(
            "Rust Analyzer Language Server is not available. " +
            "Please, ensure its [proper installation](https://rust-analyzer.github.io/manual.html#installation)."
        );
    }

    log.info("Using server binary at", path);

    if (!isValidExecutable(path)) {
        throw new Error(`Failed to execute ${path} --version`);
    }

    return path;
}

async function patchelf(dest: PathLike): Promise<void> {
    await vscode.window.withProgress(
        {
            location: vscode.ProgressLocation.Notification,
            title: "Patching rust-analyzer for NixOS"
        },
        async (progress, _) => {
            const expression = `
            {src, pkgs ? import <nixpkgs> {}}:
                pkgs.stdenv.mkDerivation {
                    name = "rust-analyzer";
                    inherit src;
                    phases = [ "installPhase" "fixupPhase" ];
                    installPhase = "cp $src $out";
                    fixupPhase = ''
                    chmod 755 $out
                    patchelf --set-interpreter "$(cat $NIX_CC/nix-support/dynamic-linker)" $out
                    '';
                }
            `;
            const origFile = dest + "-orig";
            await fs.rename(dest, origFile);
            progress.report({ message: "Patching executable", increment: 20 });
            await new Promise((resolve, reject) => {
                const handle = exec(`nix-build -E - --arg src '${origFile}' -o ${dest}`,
                    (err, stdout, stderr) => {
                        if (err != null) {
                            reject(Error(stderr));
                        } else {
                            resolve(stdout);
                        }
                    });
                handle.stdin?.write(expression);
                handle.stdin?.end();
            });
            await fs.unlink(origFile);
        }
    );
}

async function getServer(config: Config, state: PersistentState): Promise<string | undefined> {
    const explicitPath = process.env.__RA_LSP_SERVER_DEBUG ?? config.serverPath;
    if (explicitPath) {
        if (explicitPath.startsWith("~/")) {
            return os.homedir() + explicitPath.slice("~".length);
        }
        return explicitPath;
    };
    if (config.package.releaseTag === null) return "rust-analyzer";

    let platform: string | undefined;
    if (process.arch === "x64" || process.arch === "ia32") {
        if (process.platform === "linux") platform = "linux";
        if (process.platform === "darwin") platform = "mac";
        if (process.platform === "win32") platform = "windows";
    }
    if (platform === undefined) {
        vscode.window.showErrorMessage(
            "Unfortunately we don't ship binaries for your platform yet. " +
            "You need to manually clone rust-analyzer repository and " +
            "run `cargo xtask install --server` to build the language server from sources. " +
            "If you feel that your platform should be supported, please create an issue " +
            "about that [here](https://github.com/rust-analyzer/rust-analyzer/issues) and we " +
            "will consider it."
        );
        return undefined;
    }
    const ext = platform === "windows" ? ".exe" : "";
    const dest = path.join(config.globalStoragePath, `rust-analyzer-${platform}${ext}`);
    const exists = await fs.stat(dest).then(() => true, () => false);
    if (!exists) {
        await state.updateServerVersion(undefined);
    }

    if (state.serverVersion === config.package.version) return dest;

    if (config.askBeforeDownload) {
        const userResponse = await vscode.window.showInformationMessage(
            `Language server version ${config.package.version} for rust-analyzer is not installed.`,
            "Download now"
        );
        if (userResponse !== "Download now") return dest;
    }

    const releaseTag = config.package.releaseTag;
    const release = await performDownloadWithRetryDialog(async () => {
        return await fetchRelease(releaseTag, state.githubToken);
    }, state);
    const artifact = release.assets.find(artifact => artifact.name === `rust-analyzer-${platform}.gz`);
    assert(!!artifact, `Bad release: ${JSON.stringify(release)}`);

    await performDownloadWithRetryDialog(async () => {
        // Unlinking the exe file before moving new one on its place should prevent ETXTBSY error.
        await fs.unlink(dest).catch(err => {
            if (err.code !== "ENOENT") throw err;
        });

        await download({
            url: artifact.browser_download_url,
            dest,
            progressTitle: "Downloading rust-analyzer server",
            gunzip: true,
            mode: 0o755
        });
    }, state);

    // Patching executable if that's NixOS.
    if (await fs.stat("/etc/nixos").then(_ => true).catch(_ => false)) {
        await patchelf(dest);
    }

    await state.updateServerVersion(config.package.version);
    return dest;
}

async function performDownloadWithRetryDialog<T>(downloadFunc: () => Promise<T>, state: PersistentState): Promise<T> {
    while (true) {
        try {
            return await downloadFunc();
        } catch (e) {
            const selected = await vscode.window.showErrorMessage("Failed perform download: " + e.message, {}, {
                title: "Update Github Auth Token",
                updateToken: true,
            }, {
                title: "Retry download",
                retry: true,
            }, {
                title: "Dismiss",
            });

            if (selected?.updateToken) {
                await queryForGithubToken(state);
                continue;
            } else if (selected?.retry) {
                continue;
            }
            throw e;
        };
    }
}

async function queryForGithubToken(state: PersistentState): Promise<void> {
    const githubTokenOptions: vscode.InputBoxOptions = {
        value: state.githubToken,
        password: true,
        prompt: `
            This dialog allows to store a Github authorization token.
            The usage of an authorization token will increase the rate
            limit on the use of Github APIs and can thereby prevent getting
            throttled.
            Auth tokens can be created at https://github.com/settings/tokens`,
    };

    const newToken = await vscode.window.showInputBox(githubTokenOptions);
    if (newToken !== undefined) {
        if (newToken === "") {
            log.info("Clearing github token");
            await state.updateGithubToken(undefined);
        } else {
            log.info("Storing new github token");
            await state.updateGithubToken(newToken);
        }
    }
}