import { readFileSync, writeFileSync, mkdirSync } from "node:fs";
import { dirname, join } from "node:path";
import { homedir } from "node:os";
import { performance } from "node:perf_hooks";
import { OLLAMA_URL, OLLAMA_PORT } from "../config.js";
import { getActiveChatModel } from "../runtime-config.js";
import { log, err } from "../log.js";
import type { ModelDef } from "../registry/models.js";

const BOLD = "\x1b[1m";
const DIM = "\x1b[2m";
const RESET = "\x1b[0m";

const BENCHMARKS_PATH = join(
  homedir(),
  ".config",
  "localcode",
  "benchmarks.json",
);

interface BenchPrompt {
  label: string;
  system: string;
  user: string;
}

const PROMPTS: BenchPrompt[] = [
  {
    label: "fizzbuzz",
    system: "You are an expert programmer.",
    user: "Write a fizzbuzz function in Python.",
  },
  {
    label: "BST class",
    system: "You are an expert programmer.",
    user: "Write a binary search tree implementation in TypeScript with insert, delete, and search methods.",
  },
  {
    label: "code review",
    system: "You are an expert code reviewer.",
    user: `Review this code and suggest improvements:

function processData(data) {
  var result = [];
  for (var i = 0; i < data.length; i++) {
    if (data[i].active == true) {
      var item = {};
      item.name = data[i].firstName + " " + data[i].lastName;
      item.email = data[i].email;
      item.score = data[i].points / data[i].maxPoints * 100;
      if (item.score >= 90) {
        item.grade = "A";
      } else if (item.score >= 80) {
        item.grade = "B";
      } else if (item.score >= 70) {
        item.grade = "C";
      } else if (item.score >= 60) {
        item.grade = "D";
      } else {
        item.grade = "F";
      }
      result.push(item);
    }
  }
  result.sort(function(a, b) { return b.score - a.score; });
  return result;
}`,
  },
];

interface PromptResult {
  label: string;
  promptTokens: number;
  completionTokens: number;
  elapsedMs: number;
  tokensPerSec: number;
}

interface BenchmarkEntry {
  timestamp: string;
  model: string;
  modelName: string;
  results: PromptResult[];
  avgTokPerSec: number;
}

async function checkHealth(): Promise<boolean> {
  try {
    const res = await fetch(`${OLLAMA_URL}/api/tags`);
    return res.ok;
  } catch {
    return false;
  }
}

async function runPrompt(
  model: ModelDef,
  prompt: BenchPrompt,
): Promise<PromptResult> {
  const body = JSON.stringify({
    model: model.ollamaTag,
    messages: [
      { role: "system", content: prompt.system },
      { role: "user", content: prompt.user },
    ],
    stream: false,
  });

  const start = performance.now();
  const res = await fetch(
    `${OLLAMA_URL}/v1/chat/completions`,
    {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body,
    },
  );

  if (!res.ok) {
    const text = await res.text();
    throw new Error(`Server returned ${res.status}: ${text}`);
  }

  const elapsed = performance.now() - start;
  const data = (await res.json()) as {
    usage?: { prompt_tokens?: number; completion_tokens?: number };
  };

  const promptTokens = data.usage?.prompt_tokens ?? 0;
  const completionTokens = data.usage?.completion_tokens ?? 0;
  const tokPerSec =
    completionTokens > 0 ? completionTokens / (elapsed / 1000) : 0;

  return {
    label: prompt.label,
    promptTokens,
    completionTokens,
    elapsedMs: elapsed,
    tokensPerSec: tokPerSec,
  };
}

function saveBenchmark(entry: BenchmarkEntry): void {
  let history: BenchmarkEntry[] = [];
  try {
    history = JSON.parse(
      readFileSync(BENCHMARKS_PATH, "utf-8"),
    ) as BenchmarkEntry[];
  } catch {
    // No existing file
  }
  history.push(entry);
  mkdirSync(dirname(BENCHMARKS_PATH), { recursive: true });
  writeFileSync(BENCHMARKS_PATH, JSON.stringify(history, null, 2) + "\n");
}

function printResults(model: ModelDef, results: PromptResult[]): void {
  console.log("");
  console.log(`${BOLD}Model:${RESET} ${model.name} (${model.ollamaTag})`);
  console.log(`${BOLD}Port:${RESET}  ${OLLAMA_PORT}`);
  console.log("");

  // Table header
  const hdr = [
    "Prompt".padEnd(16),
    "Prompt Tok".padStart(10),
    "Compl Tok".padStart(10),
    "Time (s)".padStart(10),
    "Tok/s".padStart(8),
  ].join("  ");
  console.log(`  ${BOLD}${hdr}${RESET}`);
  console.log(`  ${"─".repeat(hdr.length)}`);

  for (const r of results) {
    const row = [
      r.label.padEnd(16),
      String(r.promptTokens).padStart(10),
      String(r.completionTokens).padStart(10),
      (r.elapsedMs / 1000).toFixed(1).padStart(10),
      r.tokensPerSec.toFixed(1).padStart(8),
    ].join("  ");
    console.log(`  ${row}`);
  }

  const avgTokSec =
    results.reduce((s, r) => s + r.tokensPerSec, 0) / results.length;
  console.log("");
  console.log(`  ${BOLD}Average: ${avgTokSec.toFixed(1)} tok/s${RESET}`);
  console.log("");
}

function printHistory(): void {
  let history: BenchmarkEntry[] = [];
  try {
    history = JSON.parse(
      readFileSync(BENCHMARKS_PATH, "utf-8"),
    ) as BenchmarkEntry[];
  } catch {
    console.log("No benchmark history found.");
    return;
  }

  if (history.length === 0) {
    console.log("No benchmark history found.");
    return;
  }

  console.log(`\n${BOLD}Benchmark History:${RESET}\n`);
  const hdr = [
    "Date".padEnd(20),
    "Model".padEnd(24),
    "Avg Tok/s".padStart(10),
  ].join("  ");
  console.log(`  ${BOLD}${hdr}${RESET}`);
  console.log(`  ${"─".repeat(hdr.length)}`);

  for (const entry of history) {
    const date = entry.timestamp.replace("T", " ").slice(0, 19);
    const row = [
      date.padEnd(20),
      entry.modelName.padEnd(24),
      entry.avgTokPerSec.toFixed(1).padStart(10),
    ].join("  ");
    console.log(`  ${row}`);
  }
  console.log("");
}

export async function runBench(args: string[]): Promise<void> {
  if (args.includes("--history")) {
    printHistory();
    return;
  }

  const healthy = await checkHealth();
  if (!healthy) {
    err("Ollama not running. Start it with: localcode start");
  }

  const model = getActiveChatModel();
  log(`Benchmarking ${model.name} (${model.ollamaTag})...`);
  console.log(`${DIM}Running ${PROMPTS.length} prompts (this may take a minute)...${RESET}`);

  const results: PromptResult[] = [];
  for (const prompt of PROMPTS) {
    process.stdout.write(`  ${prompt.label}...`);
    try {
      const result = await runPrompt(model, prompt);
      results.push(result);
      console.log(` ${result.tokensPerSec.toFixed(1)} tok/s`);
    } catch (e) {
      console.log(` FAILED: ${e instanceof Error ? e.message : e}`);
    }
  }

  if (results.length === 0) {
    err("All prompts failed.");
  }

  printResults(model, results);

  // Save to history
  const avgTokPerSec =
    results.reduce((s, r) => s + r.tokensPerSec, 0) / results.length;
  saveBenchmark({
    timestamp: new Date().toISOString(),
    model: model.id,
    modelName: model.name,
    results,
    avgTokPerSec,
  });
  log(`Results saved to ${BENCHMARKS_PATH}`);
}