/**
 * campaign-export — plan-export transforms (v5.7 Fase 2, Block 4c).
 *
 * The second half of Block 4 ("durable backlog + execution"). Block 4b built the cross-repo
 * prioritized backlog the user picks from; this exports a picked repo's per-repo action plan
 * into the TARGET repo's OWN `docs/` directory, so the plan gets a durable, human-readable
 * home where the work is done ("planer følger arbeidsstedet" — the operator's continuity rule
 * that plans live next to the workplace, in `docs/`).
 *
 * Design mirrors campaign-ledger: PURE, deterministic transforms — `now` is injected as a
 * YYYY-MM-DD string, never read from the clock here, so they are fully unit-testable. The IO
 * (loading the ledger, reading the session's action-plan.md, writing the exported file) lives
 * in the thin `campaign-export-cli` shell. The transforms throw on programmer error
 * (missing/blank required field), consistent with the ledger transforms.
 *
 * NOTE on execution: Block 4c deliberately adds NO new execution machinery. Execution reuses
 * the existing per-repo `/config-audit implement` (which backs up every changed file, applies
 * the plan from the session, and verifies) + `/config-audit rollback`. The exported `docs/`
 * copy is the repo's durable record of the plan, NOT the execution input — `implement` still
 * reads the canonical plan from the session directory. See docs/v5.7-optimization-lens-plan.md
 * §Fase 2 (Block 4).
 */

import { join } from 'node:path';

/**
 * The exported plan's destination inside the TARGET repo's own `docs/`. Keyed on the source
 * `sessionId` (timestamp-unique per audit) rather than the calendar date, so two audits of the
 * same repo on the same day produce distinct files (history is preserved, never silently
 * overwritten) and the filename ties the export back to the audit that produced it.
 *
 * @param {string} repoPath - absolute path to the target repo (the ledger stores it resolved)
 * @param {string} sessionId - the config-audit session that produced the plan
 * @returns {string} `<repoPath>/docs/config-audit-plan-<sessionId>.md`
 */
export function planExportPath(repoPath, sessionId) {
  if (typeof repoPath !== 'string' || repoPath.trim() === '') {
    throw new TypeError('repoPath is required');
  }
  if (typeof sessionId !== 'string' || sessionId.trim() === '') {
    throw new TypeError('sessionId is required');
  }
  return join(repoPath, 'docs', `config-audit-plan-${sessionId}.md`);
}

/**
 * Assemble the exported document: a provenance header (who/when/where this came from + how to
 * execute and undo it) followed by the verbatim session plan body. Pure — given the same inputs
 * it always produces the same bytes, so it is snapshot-testable.
 *
 * @param {{repoName:string, repoPath:string, sessionId:string, planMarkdown:string, now:string}} input
 * @returns {string} the full markdown to write into the repo's docs/
 */
export function buildPlanExportDocument({ repoName, repoPath, sessionId, planMarkdown, now } = {}) {
  for (const [k, v] of Object.entries({ repoName, repoPath, sessionId, planMarkdown, now })) {
    if (typeof v !== 'string' || v.trim() === '') {
      throw new TypeError(`${k} is required`);
    }
  }

  const header = [
    `# Config-Audit Action Plan — ${repoName}`,
    '',
    `> Exported from the config-audit machine-wide campaign on ${now}.`,
    `> **Repo:** \`${repoPath}\``,
    `> **Source session:** \`${sessionId}\``,
    '>',
    '> Generated by `/config-audit plan`. To **execute**: run `/config-audit implement` in this',
    '> repo — it backs up every changed file, applies the plan, then verifies the result. To',
    '> **undo**: `/config-audit rollback`. Record progress back in the campaign with',
    `> \`/config-audit campaign set-status ${repoPath} implemented\`.`,
    '',
    '---',
    '',
  ].join('\n');

  return `${header}${planMarkdown.trimEnd()}\n`;
}