// Surface fingerprint of a live endpoint (docs/21 §Applying surfaces to a live endpoint).
// Invariant: whatever writes the configuration a running native process read at launch — a capability
// sweep, the memory provider's own provision/update verbs, `native-memory`, an operator — is applied at
// the next turn boundary. Providers write their surfaces WITHOUT going through the core, so the core
// cannot rely on being told: it records what the launch read and compares it on the supervise tick.
//
// Only files the runtime reads at launch AND that the runtime itself never writes while it runs are
// fingerprinted — a self-written file would turn every turn into a reload. Host-global configuration
// (~/.codex/config.toml, ~/.claude.json) is written by the runtimes themselves and is NOT watched; the
// core verbs that write it request a reload explicitly.
import { createHash } from 'node:crypto'
import { existsSync, readdirSync, readFileSync } from 'node:fs'
import { join } from 'node:path'
import { writeFileAtomic } from '../storage/index.ts'
import type { LifecycleConfig } from '../lifecycle/index.ts'
import { opencodePrivateDir } from '../storage/index.ts'

/** Files in the OpenCode private dir that are runtime state or regenerated by the core on every launch. */
const OPENCODE_NOT_SURFACE = new Set(['state.json', 'events.jsonl', 'control.sock', 'iapeer-plugin.mjs', 'peer-mcp.json'])

export function surfaceFiles(runtime: string, cwd: string, personality: string, env: NodeJS.ProcessEnv): string[] {
  if (runtime === 'claude') return [join(cwd, '.mcp.json'), join(cwd, '.claude', 'settings.json')]
  if (runtime === 'codex') return [join(cwd, '.codex', 'config.toml'), join(cwd, '.codex', 'hooks.json')]
  if (runtime === 'opencode') {
    const dir = opencodePrivateDir(personality, { env })
    const own = existsSync(dir) ? readdirSync(dir).filter(n => !OPENCODE_NOT_SURFACE.has(n) && /\.(json|mjs)$/.test(n)).sort().map(n => join(dir, n)) : []
    // The core projects the peer's claude/codex MCP declarations into OpenCode at launch (peer-mcp.json):
    // their sources are OpenCode surfaces too.
    return [...own, join(cwd, '.mcp.json'), join(cwd, '.codex', 'config.toml')]
  }
  return []
}

export function surfaceFingerprint(runtime: string, cwd: string, personality: string, env: NodeJS.ProcessEnv): string {
  const h = createHash('sha256')
  for (const f of surfaceFiles(runtime, cwd, personality, env)) {
    h.update(f).update('\0')
    try { h.update(readFileSync(f)) } catch { h.update('\u0000absent') }
    h.update('\0')
  }
  return h.digest('hex')
}

const baselinePath = (cfg: LifecycleConfig, identity: string): string => join(cfg.stateDir, `${identity}.surfaces`)
export function readSurfaceBaseline(cfg: LifecycleConfig, identity: string): string | undefined {
  try { return readFileSync(baselinePath(cfg, identity), 'utf8').trim() || undefined } catch { return undefined }
}
export function writeSurfaceBaseline(cfg: LifecycleConfig, identity: string, fingerprint: string): void {
  writeFileAtomic(baselinePath(cfg, identity), fingerprint + '\n')
}