import * as os from "os";
import * as vscode from "vscode";
import * as path from "path";
import type * as ra from "./lsp_ext";

import { Cargo, type ExecutableInfo, getRustcId, getSysroot } from "./toolchain";
import type { Ctx } from "./ctx";
import { prepareEnv } from "./run";
import { unwrapUndefinable } from "./undefinable";

const debugOutput = vscode.window.createOutputChannel("Debug");
type DebugConfigProvider = (
    config: ra.Runnable,
    executable: string,
    cargoWorkspace: string,
    env: Record<string, string>,
    sourceFileMap?: Record<string, string>,
) => vscode.DebugConfiguration;

export async function makeDebugConfig(ctx: Ctx, runnable: ra.Runnable): Promise<void> {
    const scope = ctx.activeRustEditor?.document.uri;
    if (!scope) return;

    const debugConfig = await getDebugConfiguration(ctx, runnable);
    if (!debugConfig) return;

    const wsLaunchSection = vscode.workspace.getConfiguration("launch", scope);
    const configurations = wsLaunchSection.get<any[]>("configurations") || [];

    const index = configurations.findIndex((c) => c.name === debugConfig.name);
    if (index !== -1) {
        const answer = await vscode.window.showErrorMessage(
            `Launch configuration '${debugConfig.name}' already exists!`,
            "Cancel",
            "Update",
        );
        if (answer === "Cancel") return;

        configurations[index] = debugConfig;
    } else {
        configurations.push(debugConfig);
    }

    await wsLaunchSection.update("configurations", configurations);
}

export async function startDebugSession(ctx: Ctx, runnable: ra.Runnable): Promise<boolean> {
    let debugConfig: vscode.DebugConfiguration | undefined = undefined;
    let message = "";

    const wsLaunchSection = vscode.workspace.getConfiguration("launch");
    const configurations = wsLaunchSection.get<any[]>("configurations") || [];

    const index = configurations.findIndex((c) => c.name === runnable.label);
    if (-1 !== index) {
        debugConfig = configurations[index];
        message = " (from launch.json)";
        debugOutput.clear();
    } else {
        debugConfig = await getDebugConfiguration(ctx, runnable);
    }

    if (!debugConfig) return false;

    debugOutput.appendLine(`Launching debug configuration${message}:`);
    debugOutput.appendLine(JSON.stringify(debugConfig, null, 2));
    return vscode.debug.startDebugging(undefined, debugConfig);
}

function createCommandLink(extensionId: string): string {
    // do not remove the second quotes inside
    // encodeURIComponent or it won't work
    return `extension.open?${encodeURIComponent(`"${extensionId}"`)}`;
}

async function getDebugConfiguration(
    ctx: Ctx,
    runnable: ra.Runnable,
): Promise<vscode.DebugConfiguration | undefined> {
    const editor = ctx.activeRustEditor;
    if (!editor) return;

    const knownEngines: Record<string, DebugConfigProvider> = {
        "vadimcn.vscode-lldb": getLldbDebugConfig,
        "ms-vscode.cpptools": getCppvsDebugConfig,
    };
    const debugOptions = ctx.config.debug;

    let debugEngine = null;
    if (debugOptions.engine === "auto") {
        for (var engineId in knownEngines) {
            debugEngine = vscode.extensions.getExtension(engineId);
            if (debugEngine) break;
        }
    } else if (debugOptions.engine) {
        debugEngine = vscode.extensions.getExtension(debugOptions.engine);
    }

    if (!debugEngine) {
        const commandCodeLLDB: string = createCommandLink("vadimcn.vscode-lldb");
        const commandCpp: string = createCommandLink("ms-vscode.cpptools");

        await vscode.window.showErrorMessage(
            `Install [CodeLLDB](command:${commandCodeLLDB} "Open CodeLLDB")` +
                ` or [C/C++](command:${commandCpp} "Open C/C++") extension for debugging.`,
        );
        return;
    }

    debugOutput.clear();
    if (ctx.config.debug.openDebugPane) {
        debugOutput.show(true);
    }
    // folder exists or RA is not active.
    // eslint-disable-next-line @typescript-eslint/no-unnecessary-type-assertion
    const workspaceFolders = vscode.workspace.workspaceFolders!;
    const isMultiFolderWorkspace = workspaceFolders.length > 1;
    const firstWorkspace = workspaceFolders[0];
    const maybeWorkspace =
        !isMultiFolderWorkspace || !runnable.args.workspaceRoot
            ? firstWorkspace
            : workspaceFolders.find((w) => runnable.args.workspaceRoot?.includes(w.uri.fsPath)) ||
              firstWorkspace;

    const workspace = unwrapUndefinable(maybeWorkspace);
    const wsFolder = path.normalize(workspace.uri.fsPath);
    const workspaceQualifier = isMultiFolderWorkspace ? `:${workspace.name}` : "";
    function simplifyPath(p: string): string {
        // see https://github.com/rust-lang/rust-analyzer/pull/5513#issuecomment-663458818 for why this is needed
        return path.normalize(p).replace(wsFolder, "${workspaceFolder" + workspaceQualifier + "}");
    }

    const env = prepareEnv(runnable, ctx.config.runnablesExtraEnv);
    const { executable, workspace: cargoWorkspace } = await getDebugExecutableInfo(runnable, env);
    let sourceFileMap = debugOptions.sourceFileMap;
    if (sourceFileMap === "auto") {
        // let's try to use the default toolchain
        const [commitHash, sysroot] = await Promise.all([
            getRustcId(wsFolder),
            getSysroot(wsFolder),
        ]);
        const rustlib = path.normalize(sysroot + "/lib/rustlib/src/rust");
        sourceFileMap = {};
        sourceFileMap[`/rustc/${commitHash}/`] = rustlib;
    }

    const provider = unwrapUndefinable(knownEngines[debugEngine.id]);
    const debugConfig = provider(
        runnable,
        simplifyPath(executable),
        cargoWorkspace,
        env,
        sourceFileMap,
    );
    if (debugConfig.type in debugOptions.engineSettings) {
        const settingsMap = (debugOptions.engineSettings as any)[debugConfig.type];
        for (var key in settingsMap) {
            debugConfig[key] = settingsMap[key];
        }
    }

    if (debugConfig.name === "run binary") {
        // The LSP side: crates\rust-analyzer\src\main_loop\handlers.rs,
        // fn to_lsp_runnable(...) with RunnableKind::Bin
        debugConfig.name = `run ${path.basename(executable)}`;
    }

    const cwd = debugConfig["cwd"];
    if (cwd) {
        debugConfig["cwd"] = simplifyPath(cwd);
    }

    return debugConfig;
}

async function getDebugExecutableInfo(
    runnable: ra.Runnable,
    env: Record<string, string>,
): Promise<ExecutableInfo> {
    const cargo = new Cargo(runnable.args.workspaceRoot || ".", debugOutput, env);
    const executableInfo = await cargo.executableInfoFromArgs(runnable.args.cargoArgs);

    // if we are here, there were no compilation errors.
    return executableInfo;
}

function getLldbDebugConfig(
    runnable: ra.Runnable,
    executable: string,
    cargoWorkspace: string,
    env: Record<string, string>,
    sourceFileMap?: Record<string, string>,
): vscode.DebugConfiguration {
    return {
        type: "lldb",
        request: "launch",
        name: runnable.label,
        program: executable,
        args: runnable.args.executableArgs,
        cwd: cargoWorkspace || runnable.args.workspaceRoot,
        sourceMap: sourceFileMap,
        sourceLanguages: ["rust"],
        env,
    };
}

function getCppvsDebugConfig(
    runnable: ra.Runnable,
    executable: string,
    cargoWorkspace: string,
    env: Record<string, string>,
    sourceFileMap?: Record<string, string>,
): vscode.DebugConfiguration {
    return {
        type: os.platform() === "win32" ? "cppvsdbg" : "cppdbg",
        request: "launch",
        name: runnable.label,
        program: executable,
        args: runnable.args.executableArgs,
        cwd: cargoWorkspace || runnable.args.workspaceRoot,
        sourceFileMap,
        env,
    };
}