import * as fs from 'node:fs';
import * as path from 'node:path';
import * as os from 'node:os';

export type LineLayoutType = 'compact' | 'expanded';

export type AutocompactBufferMode = 'enabled' | 'disabled';

export interface HudConfig {
  lineLayout: LineLayoutType;
  showSeparators: boolean;
  pathLevels: 1 | 2 | 3;
  gitStatus: {
    enabled: boolean;
    showDirty: boolean;
    showAheadBehind: boolean;
    showFileStats: boolean;
  };
  display: {
    showModel: boolean;
    showContextBar: boolean;
    showConfigCounts: boolean;
    showDuration: boolean;
    showTokenBreakdown: boolean;
    showUsage: boolean;
    showTools: boolean;
    showAgents: boolean;
    showTodos: boolean;
    autocompactBuffer: AutocompactBufferMode;
    usageThreshold: number;
    environmentThreshold: number;
  };
}

export const DEFAULT_CONFIG: HudConfig = {
  lineLayout: 'expanded',
  showSeparators: false,
  pathLevels: 1,
  gitStatus: {
    enabled: true,
    showDirty: true,
    showAheadBehind: false,
    showFileStats: false,
  },
  display: {
    showModel: true,
    showContextBar: true,
    showConfigCounts: true,
    showDuration: true,
    showTokenBreakdown: true,
    showUsage: true,
    showTools: true,
    showAgents: true,
    showTodos: true,
    autocompactBuffer: 'enabled',
    usageThreshold: 0,
    environmentThreshold: 0,
  },
};

export function getConfigPath(): string {
  const homeDir = os.homedir();
  return path.join(homeDir, '.claude', 'plugins', 'claude-hud', 'config.json');
}

function validatePathLevels(value: unknown): value is 1 | 2 | 3 {
  return value === 1 || value === 2 || value === 3;
}

function validateLineLayout(value: unknown): value is LineLayoutType {
  return value === 'compact' || value === 'expanded';
}

function validateAutocompactBuffer(value: unknown): value is AutocompactBufferMode {
  return value === 'enabled' || value === 'disabled';
}

interface LegacyConfig {
  layout?: 'default' | 'separators';
}

function migrateConfig(userConfig: Partial<HudConfig> & LegacyConfig): Partial<HudConfig> {
  const migrated = { ...userConfig } as Partial<HudConfig> & LegacyConfig;

  if ('layout' in userConfig && !('lineLayout' in userConfig)) {
    if (userConfig.layout === 'separators') {
      migrated.lineLayout = 'compact';
      migrated.showSeparators = true;
    } else {
      migrated.lineLayout = 'compact';
      migrated.showSeparators = false;
    }
    delete migrated.layout;
  }

  return migrated;
}

function validateThreshold(value: unknown, max = 100): number {
  if (typeof value !== 'number') return 0;
  return Math.max(0, Math.min(max, value));
}

function mergeConfig(userConfig: Partial<HudConfig>): HudConfig {
  const migrated = migrateConfig(userConfig);

  const lineLayout = validateLineLayout(migrated.lineLayout)
    ? migrated.lineLayout
    : DEFAULT_CONFIG.lineLayout;

  const showSeparators = typeof migrated.showSeparators === 'boolean'
    ? migrated.showSeparators
    : DEFAULT_CONFIG.showSeparators;

  const pathLevels = validatePathLevels(migrated.pathLevels)
    ? migrated.pathLevels
    : DEFAULT_CONFIG.pathLevels;

  const gitStatus = {
    enabled: typeof migrated.gitStatus?.enabled === 'boolean'
      ? migrated.gitStatus.enabled
      : DEFAULT_CONFIG.gitStatus.enabled,
    showDirty: typeof migrated.gitStatus?.showDirty === 'boolean'
      ? migrated.gitStatus.showDirty
      : DEFAULT_CONFIG.gitStatus.showDirty,
    showAheadBehind: typeof migrated.gitStatus?.showAheadBehind === 'boolean'
      ? migrated.gitStatus.showAheadBehind
      : DEFAULT_CONFIG.gitStatus.showAheadBehind,
    showFileStats: typeof migrated.gitStatus?.showFileStats === 'boolean'
      ? migrated.gitStatus.showFileStats
      : DEFAULT_CONFIG.gitStatus.showFileStats,
  };

  const display = {
    showModel: typeof migrated.display?.showModel === 'boolean'
      ? migrated.display.showModel
      : DEFAULT_CONFIG.display.showModel,
    showContextBar: typeof migrated.display?.showContextBar === 'boolean'
      ? migrated.display.showContextBar
      : DEFAULT_CONFIG.display.showContextBar,
    showConfigCounts: typeof migrated.display?.showConfigCounts === 'boolean'
      ? migrated.display.showConfigCounts
      : DEFAULT_CONFIG.display.showConfigCounts,
    showDuration: typeof migrated.display?.showDuration === 'boolean'
      ? migrated.display.showDuration
      : DEFAULT_CONFIG.display.showDuration,
    showTokenBreakdown: typeof migrated.display?.showTokenBreakdown === 'boolean'
      ? migrated.display.showTokenBreakdown
      : DEFAULT_CONFIG.display.showTokenBreakdown,
    showUsage: typeof migrated.display?.showUsage === 'boolean'
      ? migrated.display.showUsage
      : DEFAULT_CONFIG.display.showUsage,
    showTools: typeof migrated.display?.showTools === 'boolean'
      ? migrated.display.showTools
      : DEFAULT_CONFIG.display.showTools,
    showAgents: typeof migrated.display?.showAgents === 'boolean'
      ? migrated.display.showAgents
      : DEFAULT_CONFIG.display.showAgents,
    showTodos: typeof migrated.display?.showTodos === 'boolean'
      ? migrated.display.showTodos
      : DEFAULT_CONFIG.display.showTodos,
    autocompactBuffer: validateAutocompactBuffer(migrated.display?.autocompactBuffer)
      ? migrated.display.autocompactBuffer
      : DEFAULT_CONFIG.display.autocompactBuffer,
    usageThreshold: validateThreshold(migrated.display?.usageThreshold, 100),
    environmentThreshold: validateThreshold(migrated.display?.environmentThreshold, 100),
  };

  return { lineLayout, showSeparators, pathLevels, gitStatus, display };
}

export async function loadConfig(): Promise<HudConfig> {
  const configPath = getConfigPath();

  try {
    if (!fs.existsSync(configPath)) {
      return DEFAULT_CONFIG;
    }

    const content = fs.readFileSync(configPath, 'utf-8');
    const userConfig = JSON.parse(content) as Partial<HudConfig>;
    return mergeConfig(userConfig);
  } catch {
    return DEFAULT_CONFIG;
  }
}