import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";

import { isInitialized } from "../utils.js";

/**
 * Register event handlers for the docgraph extension.
 *
 * - session_start: notify user if docgraph is not initialized
 * - before_agent_start: inject docgraph context into the system prompt
 */
export function registerEvents(pi: ExtensionAPI): void {
  // Notify on session start if docgraph isn't initialized
  pi.on("session_start", async (_event, ctx) => {
    if (!isInitialized(ctx)) {
      ctx.ui.setStatus(
        "docgraph",
        "Docgraph: not initialized — ask agent to run docgraph_init",
      );
    } else {
      ctx.ui.setStatus("docgraph", "Docgraph: initialized");
    }
  });

  // Inject docgraph context into the system prompt so the AI knows about it
  pi.on("before_agent_start", async (event, ctx) => {
    const initialized = isInitialized(ctx);

    if (!initialized) {
      // If not initialized, let the AI know it can scaffold docs
      return {
        systemPrompt:
          (event.systemPrompt ?? "") +
          [
            "",
            "## Docgraph (AI-Native Documentation Graph)",
            "",
            "This project uses **pi-docgraph**, an AI-native documentation system.",
            "The documentation has NOT been initialized yet.",
            "",
            "Use the `docgraph_init` tool to scaffold the documentation structure:",
            "- AGENTS.md (AI entry point)",
            "- README.md (human entry point)",
            "- docs/SPEC.md, ARCHITECTURE.md, API.md, DESIGN.md",
            "- docs/ROADMAP.md, BACKLOG.md",
            "- docs/tickets/ (implementation tickets)",
            "",
            "After initialization:",
            `- Use \`docgraph_read\` to read a document's metadata and body`,
            `- Use \`docgraph_sync\` to validate cross-references after code changes`,
            `- Use \`docgraph_update\` to modify document fields`,
            `- Use \`docgraph_ticket_create\`, \`docgraph_ticket_update\`, \`docgraph_ticket_list\` for ticket-driven workflows`,
            "",
            "When implementing tickets, follow the Ticket Completion & Verification Rules section in AGENTS.md.",
            "Always treat the codebase as the source of truth.",
          ].join("\n"),
      };
    }

    // If initialized, add a minimal context line
    return {
      systemPrompt:
        (event.systemPrompt ?? "") +
        [
          "",
          "## Docgraph",
          "",
          "This project uses pi-docgraph for AI-native documentation.",
          `Use \`docgraph_read\` to read docs, \`docgraph_sync\` to validate links,`,
          `\`docgraph_ticket_list\` to view the work queue, and \`docgraph_ticket_update\` to move tickets.`,
          "The codebase is always the source of truth.",
        ].join("\n"),
    };
  });
}