import * as vscode from 'vscode';
import * as fs from 'fs';
import * as path from 'path';
import { SolutionModel } from './model';
import { taskLabel } from './tasks';

export const LAUNCH_NAME = '.NET Solution: Debug startup project';

function launchSettings() {
    return vscode.workspace.getConfiguration('dotnetSolution');
}

/** Launch options for one project, from settings or launchSettings.json. */
export interface ProjectLaunchOptions {
    args?: string[];
    env?: Record<string, string>;
    cwd?: string;
    console?: string;
    /** Profile name in Properties/launchSettings.json; empty picks the first "Project" profile. */
    profile?: string;
}

interface LaunchProfile {
    commandName?: string;
    commandLineArgs?: string;
    workingDirectory?: string;
    environmentVariables?: Record<string, string>;
}

/** Splits a launchSettings commandLineArgs string the way the SDK does: on whitespace, honouring quotes. */
export function splitCommandLine(text: string): string[] {
    const args: string[] = [];
    const pattern = /"((?:[^"\\]|\\.)*)"|'([^']*)'|(\S+)/g;
    for (const match of text.matchAll(pattern)) {
        args.push(match[1] !== undefined ? match[1].replace(/\\(.)/g, '$1') : match[2] ?? match[3]);
    }
    return args;
}

/** Reads the profile that applies to a project, if it has a Properties/launchSettings.json. */
export function readLaunchProfile(projectPath: string, profileName: string | undefined): LaunchProfile | undefined {
    const file = path.join(path.dirname(projectPath), 'Properties', 'launchSettings.json');
    if (!fs.existsSync(file)) {
        return undefined;
    }
    try {
        const profiles: Record<string, LaunchProfile> = JSON.parse(fs.readFileSync(file, 'utf8')).profiles ?? {};
        if (profileName) {
            return profiles[profileName];
        }
        // The first profile that launches the project itself, not IIS Express or a container.
        return Object.values(profiles).find(profile => (profile.commandName ?? 'Project') === 'Project')
            ?? Object.values(profiles)[0];
    } catch {
        return undefined;
    }
}

/**
 * The launch options for one project: per-project settings override the global ones,
 * and both override Properties/launchSettings.json.
 *
 * Builder and Editor want different arguments and working directories, which is why
 * `dotnetSolution.launch.projects` is keyed by project name.
 */
export function launchOptionsFor(projectName: string, projectPath: string, projectDir: string): Required<Pick<ProjectLaunchOptions, 'args' | 'env' | 'console'>> & { cwd: string | undefined } {
    const settings = launchSettings();
    const perProject = settings.get<Record<string, ProjectLaunchOptions>>('launch.projects', {});
    const own = perProject[projectName] ?? {};
    const profile = readLaunchProfile(projectPath, own.profile ?? settings.get<string>('launch.profile', ''));

    const args = own.args ?? (settings.get<string[]>('launch.args', []).length
        ? settings.get<string[]>('launch.args', [])
        : profile?.commandLineArgs ? splitCommandLine(profile.commandLineArgs) : []);
    const env = { ...(profile?.environmentVariables ?? {}), ...settings.get<Record<string, string>>('launch.env', {}), ...(own.env ?? {}) };
    const rawCwd = own.cwd ?? settings.get<string>('launch.cwd', '') ?? '';
    const cwd = rawCwd
        ? path.resolve(projectDir, rawCwd)
        : profile?.workingDirectory ? path.resolve(projectDir, profile.workingDirectory) : undefined;
    const console = own.console ?? settings.get<string>('launch.console', 'internalConsole');
    return { args, env, cwd, console };
}

/**
 * A complete launch configuration for the startup project under the active configuration.
 *
 * `program` is the apphost .exe when the project makes one, because vsdbg wants an
 * executable. Projects without an apphost run through the dotnet host instead. The
 * debugger options DotRush normally fills in (justMyCode, symbol servers) are left out so
 * its own provider still adds them.
 */
export async function buildLaunchConfiguration(
    model: SolutionModel, options: { noDebug?: boolean; preLaunchTask?: string }): Promise<vscode.DebugConfiguration> {
    const active = model.active;
    if (!active) {
        throw new Error('No startup project selected.');
    }
    const target = await model.resolveTarget();
    const info = active.project.info;
    const launch = launchOptionsFor(info.name, info.fsPath, path.dirname(info.fsPath));
    const cwd = launch.cwd ?? target.targetDir.replace(/[\\/]+$/, '');

    const program = target.executablePath ?? 'dotnet';
    const args = target.executablePath ? launch.args : [target.targetPath, ...launch.args];

    return {
        name: `${info.name} (${active.solutionConfiguration.configuration}|${active.solutionPlatform})`,
        type: launchSettings().get<string>('debugType', 'coreclr'),
        request: 'launch',
        program,
        args,
        cwd,
        env: launch.env,
        console: launch.console,
        noDebug: options.noDebug ?? false,
        preLaunchTask: options.preLaunchTask,
        // launchSettings.json is applied above so per-project settings can override it.
        // DotRush still points vsdbg at the file; vsdbg only takes commandLineArgs from it
        // when `args` is empty, and the environment merge is idempotent.
    };
}

/** The static entry written to launch.json: values come back through `${command:…}` at launch time. */
export function launchJsonEntry(): Record<string, unknown> {
    return {
        name: LAUNCH_NAME,
        type: launchSettings().get<string>('debugType', 'coreclr'),
        request: 'launch',
        program: '${command:dotnetSolution.activeProgram}',
        args: [],
        cwd: '${command:dotnetSolution.activeCwd}',
        preLaunchTask: taskLabel('build'),
    };
}

/**
 * Offers the dynamic "debug the startup project" entry in the Run and Debug dropdown,
 * and fills in `program` for launch.json entries that use this extension's variables
 * but omitted them.
 */
export class SolutionDebugConfigurationProvider implements vscode.DebugConfigurationProvider {
    constructor(private readonly model: SolutionModel) { }

    async provideDebugConfigurations(): Promise<vscode.DebugConfiguration[]> {
        if (!this.model.active) {
            return [];
        }
        return [launchJsonEntry() as vscode.DebugConfiguration];
    }

    /**
     * The launch.json entry carries no arguments, since ${command:} variables can only be
     * strings. Fill in the per-project options here so F5 behaves like the debug button.
     */
    resolveDebugConfiguration(_folder: vscode.WorkspaceFolder | undefined, config: vscode.DebugConfiguration): vscode.DebugConfiguration {
        const active = this.model.active;
        if (config.name !== LAUNCH_NAME || !active) {
            return config;
        }
        const info = active.project.info;
        const launch = launchOptionsFor(info.name, info.fsPath, path.dirname(info.fsPath));
        if (!config.args || (Array.isArray(config.args) && config.args.length === 0)) {
            config.args = launch.args;
        }
        config.env = { ...launch.env, ...(config.env ?? {}) };
        config.console ??= launch.console;
        return config;
    }
}