/**
 * Context Handler - SessionStart
 *
 * Extracted from context-hook.ts - calls worker to generate context.
 * Returns context as hookSpecificOutput for Claude Code to inject.
 */

import type { EventHandler, NormalizedHookInput, HookResult } from '../types.js';
import {
  executeWithWorkerFallback,
  isWorkerFallback,
  getWorkerPort,
} from '../../shared/worker-utils.js';
import { getProjectContext } from '../../utils/project-name.js';
import { HOOK_EXIT_CODES } from '../../shared/hook-constants.js';
import { logger } from '../../utils/logger.js';
import { loadFromFileOnce } from '../../shared/hook-settings.js';

export const contextHandler: EventHandler = {
  async execute(input: NormalizedHookInput): Promise<HookResult> {
    const cwd = input.cwd ?? process.cwd();
    const context = getProjectContext(cwd);
    const port = getWorkerPort();

    // Plan 05 Phase 4: settings via process-scope cache.
    const settings = loadFromFileOnce();
    const showTerminalOutput = settings.CLAUDE_MEM_CONTEXT_SHOW_TERMINAL_OUTPUT === 'true';

    // Pass all projects (parent + worktree if applicable) for unified timeline
    const projectsParam = context.allProjects.join(',');
    const apiPath = `/api/context/inject?projects=${encodeURIComponent(projectsParam)}`;
    const colorApiPath = input.platform === 'claude-code' ? `${apiPath}&colors=true` : apiPath;

    const emptyResult: HookResult = {
      hookSpecificOutput: { hookEventName: 'SessionStart', additionalContext: '' },
      exitCode: HOOK_EXIT_CODES.SUCCESS,
    };

    // Plan 05 Phase 2: single helper for ensure-worker-alive → request → fallback.
    const contextResult = await executeWithWorkerFallback<string>(apiPath, 'GET');
    if (isWorkerFallback(contextResult)) {
      return emptyResult;
    }

    let additionalContext: string;
    if (typeof contextResult === 'string') {
      additionalContext = contextResult.trim();
    } else if (contextResult === undefined) {
      additionalContext = '';
    } else {
      // Unexpected non-string body — log and fall back to empty.
      logger.warn('HOOK', 'Context response was not a string', { type: typeof contextResult });
      return emptyResult;
    }

    let coloredTimeline = '';
    if (showTerminalOutput) {
      const colorResult = await executeWithWorkerFallback<string>(colorApiPath, 'GET');
      if (!isWorkerFallback(colorResult) && typeof colorResult === 'string') {
        coloredTimeline = colorResult.trim();
      }
    }

    const platform = input.platform;

    // Use colored timeline for display if available, otherwise fall back to
    // plain markdown context (especially useful for platforms like Gemini
    // where we want to ensure visibility even if colors aren't fetched).
    const displayContent = coloredTimeline || (platform === 'gemini-cli' || platform === 'gemini' ? additionalContext : '');

    const systemMessage = showTerminalOutput && displayContent
      ? `${displayContent}\n\nView Observations Live @ http://localhost:${port}`
      : undefined;

    return {
      hookSpecificOutput: {
        hookEventName: 'SessionStart',
        additionalContext
      },
      systemMessage
    };
  }
};