import * as fs from 'fs';
import * as path from 'path';
import * as os from 'os';
import { LanguageConfig } from '../config';

export interface LanguagePreset {
  config: LanguageConfig;
  template: string;
  filename: string;
}

export type PresetMap = Record<string, LanguagePreset>;

const DEFAULT_CPP_TEMPLATE = `#include <bits/stdc++.h>
using namespace std;

int main() {
    // Solve the problem here
    return 0;
}
`;

const DEFAULT_PYTHON_TEMPLATE = `# Solve the problem here
`;

const DEFAULT_RUST_TEMPLATE = `fn main() {
    // Solve the problem here
}
`;

const DEFAULT_TYPESCRIPT_TEMPLATE = `// Solve the problem here
`;

const DEFAULT_JAVASCRIPT_TEMPLATE = `// Solve the problem here
`;

const DEFAULT_C_TEMPLATE = `#include <stdio.h>

int main() {
    // Solve the problem here
    return 0;
}
`;

const DEFAULT_PRESETS: PresetMap = {
  cpp: {
    config: {
      extension: 'cpp',
      templateDir: 'templates/cpp',
      build: 'g++ -O2 -std=gnu++20 -o a.out {{file: main.cpp}}',
      run: './a.out',
      submitFile: '{{file: main.cpp}}',
      atcoderLanguage: '',
      atcoderLanguageIdRegex: ''
    },
    template: DEFAULT_CPP_TEMPLATE,
    filename: 'main.cpp'
  },
  python: {
    config: {
      extension: 'py',
      templateDir: 'templates/python',
      build: '',
      run: 'python3 {{file: main.py}}',
      submitFile: '{{file: main.py}}',
      atcoderLanguage: '',
      atcoderLanguageIdRegex: ''
    },
    template: DEFAULT_PYTHON_TEMPLATE,
    filename: 'main.py'
  },
  rust: {
    config: {
      extension: 'rs',
      templateDir: 'templates/rust',
      build: 'rustc -O -o a.out {{file: main.rs}}',
      run: './a.out',
      submitFile: '{{file: main.rs}}',
      atcoderLanguage: '',
      atcoderLanguageIdRegex: ''
    },
    template: DEFAULT_RUST_TEMPLATE,
    filename: 'main.rs'
  },
  typescript: {
    config: {
      extension: 'ts',
      templateDir: 'templates/typescript',
      build: '',
      run: 'npx ts-node {{file: main.ts}}',
      submitFile: '{{file: main.ts}}',
      atcoderLanguage: '',
      atcoderLanguageIdRegex: ''
    },
    template: DEFAULT_TYPESCRIPT_TEMPLATE,
    filename: 'main.ts'
  },
  javascript: {
    config: {
      extension: 'js',
      templateDir: 'templates/javascript',
      build: '',
      run: 'node {{file: main.js}}',
      submitFile: '{{file: main.js}}',
      atcoderLanguage: '',
      atcoderLanguageIdRegex: ''
    },
    template: DEFAULT_JAVASCRIPT_TEMPLATE,
    filename: 'main.js'
  },
  c: {
    config: {
      extension: 'c',
      templateDir: 'templates/c',
      build: 'gcc -O2 -std=c11 -o a.out {{file: main.c}}',
      run: './a.out',
      submitFile: '{{file: main.c}}',
      atcoderLanguage: '',
      atcoderLanguageIdRegex: ''
    },
    template: DEFAULT_C_TEMPLATE,
    filename: 'main.c'
  }
};

function getGlobalSettingsDir(): string {
  return path.join(os.homedir(), '.atcoder-next');
}

export function getLanguagePresets(): PresetMap {
  const dir = getGlobalSettingsDir();
  const filePath = path.join(dir, 'languages.json');

  if (!fs.existsSync(dir)) {
    fs.mkdirSync(dir, { recursive: true });
  }

  let loadedPresets: PresetMap | null = null;

  if (fs.existsSync(filePath)) {
    try {
      const data = fs.readFileSync(filePath, 'utf8');
      loadedPresets = JSON.parse(data) as PresetMap;
    } catch {
      // Ignore parse errors
    }
  }

  if (loadedPresets) {
    let migrated = false;
    for (const [langKey, defaultPreset] of Object.entries(DEFAULT_PRESETS)) {
      const userPreset = loadedPresets[langKey];
      if (userPreset && userPreset.config) {
        if (langKey === 'cpp') {
          if (userPreset.config.build === 'g++ -O2 -std=gnu++20 -o a.out main.cpp') {
            userPreset.config.build = 'g++ -O2 -std=gnu++20 -o a.out {{file: main.cpp}}';
            migrated = true;
          }
          if (userPreset.config.submitFile === 'main.cpp') {
            userPreset.config.submitFile = '{{file: main.cpp}}';
            migrated = true;
          }
        }
        if (langKey === 'python') {
          if (userPreset.config.run === 'python3 main.py') {
            userPreset.config.run = 'python3 {{file: main.py}}';
            migrated = true;
          }
          if (userPreset.config.submitFile === 'main.py') {
            userPreset.config.submitFile = '{{file: main.py}}';
            migrated = true;
          }
        }
        if (langKey === 'rust') {
          if (userPreset.config.build === 'rustc -O -o a.out main.rs') {
            userPreset.config.build = 'rustc -O -o a.out {{file: main.rs}}';
            migrated = true;
          }
          if (userPreset.config.submitFile === 'main.rs') {
            userPreset.config.submitFile = '{{file: main.rs}}';
            migrated = true;
          }
        }
        if (langKey === 'typescript') {
          if (userPreset.config.run === 'npx ts-node main.ts') {
            userPreset.config.run = 'npx ts-node {{file: main.ts}}';
            migrated = true;
          }
          if (userPreset.config.submitFile === 'main.ts') {
            userPreset.config.submitFile = '{{file: main.ts}}';
            migrated = true;
          }
        }
        if (langKey === 'javascript') {
          if (userPreset.config.run === 'node main.js') {
            userPreset.config.run = 'node {{file: main.js}}';
            migrated = true;
          }
          if (userPreset.config.submitFile === 'main.js') {
            userPreset.config.submitFile = '{{file: main.js}}';
            migrated = true;
          }
        }
        if (langKey === 'c') {
          if (userPreset.config.build === 'gcc -O2 -std=c11 -o a.out main.c') {
            userPreset.config.build = 'gcc -O2 -std=c11 -o a.out {{file: main.c}}';
            migrated = true;
          }
          if (userPreset.config.submitFile === 'main.c') {
            userPreset.config.submitFile = '{{file: main.c}}';
            migrated = true;
          }
        }
      } else if (!userPreset) {
        loadedPresets[langKey] = defaultPreset;
        migrated = true;
      }
    }

    if (migrated) {
      try {
        fs.writeFileSync(filePath, JSON.stringify(loadedPresets, null, 2), { mode: 0o600 });
      } catch {
        // Ignore write errors
      }
    }
    return loadedPresets;
  }

  // Seed default presets if file does not exist or fails to parse
  try {
    fs.writeFileSync(filePath, JSON.stringify(DEFAULT_PRESETS, null, 2), { mode: 0o600 });
  } catch {
    // Ignore write errors
  }

  return DEFAULT_PRESETS;
}

export function saveLanguagePreset(langName: string, preset: LanguagePreset) {
  const dir = getGlobalSettingsDir();
  const filePath = path.join(dir, 'languages.json');

  const presets = getLanguagePresets();
  presets[langName] = preset;

  if (!fs.existsSync(dir)) {
    fs.mkdirSync(dir, { recursive: true });
  }

  fs.writeFileSync(filePath, JSON.stringify(presets, null, 2), { mode: 0o600 });
}