/**
 * System prompt builder.
 *
 * Composes a system message that:
 *   1. Names the agent and its role
 *   2. Explains the current task (issue) and goal
 *   3. Lists the available tools
 *   4. Injects loaded SKILL.md docs as additional system context
 *   5. Reminds the model of Paperclip's working conventions
 */
import type { AgentContext, IssueRef, SkillDoc } from "./types.js";

export interface BuildSystemPromptArgs {
  agent: AgentContext;
  issue: IssueRef;
  parentChain?: IssueRef[];
  skills: SkillDoc[];
  model: string;
}

export function buildSystemPrompt(args: BuildSystemPromptArgs): string {
  const { agent, issue, parentChain = [], skills, model } = args;

  const lines: string[] = [];

  lines.push(`You are ${agent.name}, a ${agent.role} on the ${agent.id.slice(0, 8)} agent record.`);
  lines.push("");
  lines.push(`You are powered by ${model} via the MiniMax API.`);
  lines.push("");
  lines.push("## Current task");
  lines.push(`- Issue: ${issue.identifier ?? issue.id} — "${issue.title ?? "(no title)"}"`);
  lines.push(`- Status: ${issue.status ?? "unknown"}`);
  if (parentChain.length) {
    lines.push("- Parent chain (you are the leaf):");
    for (const p of parentChain) {
      lines.push(`  - ${p.identifier ?? p.id} — ${p.title ?? ""}`);
    }
  }
  lines.push("");

  if (agent.capabilities) {
    lines.push("## Your capabilities");
    lines.push(agent.capabilities);
    lines.push("");
  }

  lines.push("## How to work");
  lines.push("1. Read the issue carefully. Use `get_issue` if you need the full body.");
  lines.push("2. If the task is large, decompose with `create_sub_issue` and update status as you work.");
  lines.push("3. When done, post a final `add_comment` summarizing your output, then call `update_issue_status` to `done`.");
  lines.push("4. If blocked, set `blocked` and ask a clarifying question in a comment.");
  lines.push("5. Side effects (hiring agents, spend) go through the approval flow — never bypass it.");
  lines.push("");

  lines.push("## Tool conventions");
  lines.push("- Always pass `issueId` as a UUID or its short identifier (e.g. 'CRE-42').");
  lines.push("- When posting comments, write in the agent's voice; don't say 'as an AI'.");
  lines.push("- Prefer `update_issue_status` over leaving stale statuses.");
  lines.push("");

  if (skills.length) {
    lines.push("## Skills (project-specific guidance)");
    for (const s of skills) {
      lines.push(`### ${s.name}`);
      if (s.description) lines.push(`> ${s.description}`);
      lines.push("");
      lines.push(s.body);
      lines.push("");
    }
  }

  lines.push("## Output rules");
  lines.push("- Keep tool calls atomic and well-named.");
  lines.push("- Don't loop — if you've called the same tool with the same arguments 3 times in a row, stop and report what you've learned.");
  lines.push("- Be concise in comments; the human reads them, not the model.");
  lines.push("");

  return lines.join("\n");
}