/**
 * AgentGuard(TM) Spend: Advisor output writers.
 *
 * Files are written locally under ~/.agentguard by default. Conversation logs
 * stay in ~/.agentguard/advisor-sessions and are never uploaded by this SDK.
 *
 * Patent notice: Protected by U.S. patent-pending technology
 * (App. Nos. 63/983,615; 63/983,621; 63/983,843; 63/984,626;
 * 64/071,781; 64/071,789).
 */

import * as fs from 'fs';
import * as os from 'os';
import * as path from 'path';
import type { SpendPolicy } from '../types';
import {
  buildPolicyFromProfile,
  formatCents,
  projectedSavings,
  type AdvisorBusinessProfile,
  type ProjectedSavings,
} from './conversation';
import { postureProfile } from './posture';

export interface AdvisorOutputOptions {
  home?: string;
  now?: Date;
  language?: 'ts' | 'py';
  overwrite?: boolean;
}

export interface AdvisorOutputs {
  policy: SpendPolicy;
  policyPath: string;
  quickstartPath: string;
  sessionDir: string;
  savings: ProjectedSavings;
  policyYaml: string;
  quickstartCode: string;
  savingsTable: string;
}

export interface AdvisorSessionLogger {
  path: string;
  append: (event: string, payload?: Record<string, unknown>) => void;
}

export function agentguardHome(): string {
  return process.env.AGENTGUARD_HOME || path.join(os.homedir(), '.agentguard');
}

export function advisorSessionDir(home = agentguardHome()): string {
  return path.join(home, 'advisor-sessions');
}

export function createAdvisorSessionLogger(home = agentguardHome(), now = new Date()): AdvisorSessionLogger {
  const dir = advisorSessionDir(home);
  fs.mkdirSync(dir, { recursive: true, mode: 0o700 });
  const stamp = now.toISOString().replace(/[:.]/g, '-');
  const file = path.join(dir, `${stamp}.jsonl`);
  fs.closeSync(fs.openSync(file, 'a', 0o600));
  return {
    path: file,
    append(event: string, payload: Record<string, unknown> = {}) {
      const line = JSON.stringify({ ts: new Date().toISOString(), event, ...payload }) + '\n';
      fs.appendFileSync(file, line, { encoding: 'utf8', mode: 0o600 });
    },
  };
}

export function writeAdvisorOutputs(profile: AdvisorBusinessProfile, options: AdvisorOutputOptions = {}): AdvisorOutputs {
  const home = options.home ?? agentguardHome();
  const language = options.language ?? profile.language;
  const sessionDir = advisorSessionDir(home);
  fs.mkdirSync(home, { recursive: true, mode: 0o700 });
  fs.mkdirSync(sessionDir, { recursive: true, mode: 0o700 });

  const policy = buildPolicyFromProfile(profile);
  const policyPath = path.join(home, 'policy.yaml');
  const quickstartPath = path.join(home, language === 'py' ? 'quickstart.py' : 'quickstart.ts');
  const savings = projectedSavings(profile);
  const policyYaml = renderPolicyYaml(policy, profile, options.now ?? new Date());
  const quickstartCode = language === 'py' ? renderQuickstartPy(policy, profile) : renderQuickstartTs(policy, profile);
  const savingsTable = renderSavingsTable(savings);

  if (!options.overwrite) {
    assertWritableTarget(policyPath);
    assertWritableTarget(quickstartPath);
  }
  atomicWrite(policyPath, policyYaml, 0o600);
  atomicWrite(quickstartPath, quickstartCode, 0o600);

  return { policy, policyPath, quickstartPath, sessionDir, savings, policyYaml, quickstartCode, savingsTable };
}

export function renderPolicyYaml(policy: SpendPolicy, profile: AdvisorBusinessProfile, now = new Date()): string {
  const caps = policy.caps.map((cap) => {
    const lines = [
      `  # WHY: ${whyForWindow(cap.window)}`,
      `  - amountCents: ${cap.amountCents}`,
      `    window: ${cap.window}`,
      `    action: ${cap.action}`,
    ];
    if (cap.downgradeTo) lines.push(`    downgradeTo: ${cap.downgradeTo}`);
    if (cap.reason) lines.push(`    reason: ${quoteYaml(cap.reason)}`);
    return lines.join('\n');
  }).join('\n');
  const tasks = profile.tasks.map((task) => `  - ${quoteYaml(task)}`).join('\n');
  const posture = postureProfile(profile.posture);
  const canary = posture.canaryPercent === undefined ? '' : `  canaryPercent: ${posture.canaryPercent}\n`;
  return `# AgentGuard Spend policy generated by agentguard advisor
# Generated at: ${now.toISOString()}
# Scope key: ${profile.scopeLabel}
id: ${policy.id}
name: ${quoteYaml(policy.name)}
version: ${policy.version}
effectiveFrom: ${quoteYaml(policy.effectiveFrom)}
mode: ${policy.mode}
requiredCapability: ${policy.requiredCapability ?? 'read_only'}
scope:
  tenantId: ${quoteYaml(policy.scope.tenantId)}
models:
  cloudFrontierPrimary: ${profile.primaryModel}
  hostedOssFallback: ${profile.hostedOssModel}
  offlineOption: ${profile.offlineModel}
  baaCoveredOption: ${profile.baaCoveredModel}
  primary: ${profile.primaryModel}
  fallback: ${profile.fallbackModel}
governancePosture:
  posture: ${profile.posture}
  auditRetentionDays: ${posture.auditRetentionDays}
  approvalGates: ${posture.approvalGates}
  downgradeStyle: ${posture.downgradeStyle}
${canary}reviewerCascade:
  default: ${profile.posture === 'compliance' ? 'always' : 'risk_triggered'}
  triageClassifier: local-3b
tasks:
${tasks}
caps:
${caps}
systemInstructions: |
${indent(systemInstructions(profile), 2)}
`;
}

export function renderQuickstartTs(policy: SpendPolicy, profile: AdvisorBusinessProfile): string {
  return `import OpenAI from 'openai';\nimport { withSpendGuard, type SpendPolicy } from '@agentguard-run/spend';\n\nconst policy: SpendPolicy = ${JSON.stringify(policy, null, 2)};\n\nconst openrouter = new OpenAI({\n  baseURL: 'https://openrouter.ai/api/v1',\n  apiKey: process.env.OPENROUTER_API_KEY,\n});\n\nexport const guardedClient = withSpendGuard(openrouter, {\n  policy,\n  scope: { tenantId: '${escapeTs(profile.tenantId)}', agentId: '${escapeTs(profile.vertical)}' },\n  capabilityClaim: '${policy.requiredCapability ?? 'read_only'}',\n});\n\nexport async function runGuardedTask(prompt: string) {\n  return guardedClient.chat.completions.create({\n    model: '${escapeTs(profile.primaryModel)}',\n    messages: [{ role: 'user', content: prompt }],\n  });\n}\n`;
}

export function renderQuickstartPy(policy: SpendPolicy, profile: AdvisorBusinessProfile): string {
  const caps = policy.caps.map((cap) => {
    const args = [`amountCents=${cap.amountCents}`, `window='${cap.window}'`, `action='${cap.action}'`];
    if (cap.downgradeTo) args.push(`downgradeTo='${escapePy(cap.downgradeTo)}'`);
    return `        SpendCap(${args.join(', ')}),`;
  }).join('\n');
  return `from openai import OpenAI\nfrom agentguard_spend import with_spend_guard\nfrom agentguard_spend.types import SpendPolicy, SpendCap\n\npolicy = SpendPolicy(\n    id='${escapePy(policy.id)}',\n    name='${escapePy(policy.name)}',\n    scope={'tenantId': '${escapePy(profile.tenantId)}'},\n    caps=[\n${caps}\n    ],\n    mode='${policy.mode}',\n    requiredCapability='${policy.requiredCapability ?? 'read_only'}',\n    version=${policy.version},\n    effectiveFrom='${escapePy(policy.effectiveFrom)}',\n)\n\nopenrouter = OpenAI(base_url='https://openrouter.ai/api/v1')\nguarded_client = with_spend_guard(\n    openrouter,\n    policy=policy,\n    scope={'tenantId': '${escapePy(profile.tenantId)}', 'agentId': '${escapePy(profile.vertical)}'},\n    capability_claim='${policy.requiredCapability ?? 'read_only'}',\n)\n`;
}

export function renderSavingsTable(savings: ProjectedSavings): string {
  const rows = [
    'Projected monthly savings',
    `Before AgentGuard: ${formatCents(savings.monthlyBeforeCents)}`,
    `After AgentGuard:  ${formatCents(savings.monthlyAfterCents)}`,
    `Savings:           ${formatCents(savings.monthlySavingsCents)} (${savings.savingsPercent}%)`,
  ];
  return rows.join('\n');
}

function atomicWrite(file: string, content: string, mode: number): void {
  const temp = `${file}.${process.pid}.${Date.now()}.tmp`;
  fs.writeFileSync(temp, content, { encoding: 'utf8', mode });
  fs.renameSync(temp, file);
  fs.chmodSync(file, mode);
}

function assertWritableTarget(file: string): void {
  if (!fs.existsSync(file)) return;
  fs.accessSync(file, fs.constants.W_OK);
}

function whyForWindow(window: string): string {
  if (window === 'per_call') return 'Bounds one agent action and routes overflow to the fallback model.';
  if (window === 'per_day') return 'Catches runaway loops and unexpected daily volume.';
  if (window === 'per_month') return 'Keeps the finance view predictable for the billing cycle.';
  return 'Limits spend inside the selected time window.';
}

function systemInstructions(profile: AdvisorBusinessProfile): string {
  const posture = postureProfile(profile.posture);
  return `Run ${profile.vertical} tasks with ${profile.requiredCapability} capability under ${posture.label} governance posture. Prefer ${profile.primaryModel} for high-value work, ${profile.hostedOssModel} for hosted OSS fallback, ${profile.offlineModel} for offline runs, and ${profile.baaCoveredModel} when a BAA-covered provider is required. Keep evidence pointers in outputs and escalate anything outside the configured capability tier.`;
}

function quoteYaml(value: string): string {
  return JSON.stringify(value);
}

function indent(value: string, spaces: number): string {
  const prefix = ' '.repeat(spaces);
  return value.split('\n').map((line) => prefix + line).join('\n');
}

function escapeTs(value: string): string {
  return value.replace(/\\/g, '\\\\').replace(/'/g, "\\'");
}

function escapePy(value: string): string {
  return value.replace(/\\/g, '\\\\').replace(/'/g, "\\'");
}