#!/usr/bin/env python3
"""Deterministic grammar fuzzing for the parser, runtime, and ownership paths.

Usage: python3 tests/drivers/fuzz_compiler.py [path/to/zy] [path/to/zym] [--js [path/to/tinyvm.js]]
(--js alone runs build/js/tinyvm.js, from make js)
"""
import random
import subprocess
import sys


argv = sys.argv[1:]
js = None
if "--js" in argv:
    k = argv.index("--js")
    del argv[k]
    js = argv.pop(k) if k < len(argv) and argv[k].endswith(".js") else "build/js/tinyvm.js"
args = argv
zy = args[0] if len(args) > 0 else "build/bin/zy"
zym = args[1] if len(args) > 1 else "build/bin/zym"
rng = random.Random(0x5A17)
values = []
library_values = []


def expr(depth):
    if depth == 0 or rng.randrange(4) == 0:
        value = rng.randrange(10)
        return str(value), value
    left, a = expr(depth - 1)
    right, b = expr(depth - 1)
    op = rng.choice(("+", "-", "*"))
    if op == "+":
        value = a + b
    elif op == "-":
        value = a - b
    else:
        value = a * b
    return f"({left} {op} {right})", value


lines = ["namespace;", "include rt, run, std;", "fn churn(n) {", " int i = 0;", " while (i < n) {", "  { int* p = rt.new(int); *p = i; }", "  i++;", " }", " return 0;", "}", "fn stable() { return 73; }", "fn main() {", " let base = rt.live_objects();"]
for _ in range(128):
    source, value = expr(4)
    lines.append(f" rt.put_n({source}); rt.put_c(32);")
    values.append(value)
for _ in range(32):
    a = "".join(rng.choice("abc") for _ in range(rng.randrange(11)))
    b = "".join(rng.choice("abc") for _ in range(rng.randrange(6)))
    lines.append(f' rt.put_n(std.Text.len("{a}")); rt.put_c(32); rt.put_n(std.Text.eq("{a}", "{b}")); rt.put_c(32);')
    lines.append(f' rt.put_n(std.Text.starts("{a}", "{b}")); rt.put_c(32); rt.put_n(std.Text.ends("{a}", "{b}")); rt.put_c(32); rt.put_n(std.Text.find("{a}", "{b}")); rt.put_c(32);')
    lines.append(f' rt.put_n(std.Bytes.len(b"{a}")); rt.put_c(32); rt.put_n(std.Bytes.eq(b"{a}", b"{b}")); rt.put_c(32);')
    lines.append(f' rt.put_n(std.Bytes.starts(b"{a}", b"{b}")); rt.put_c(32); rt.put_n(std.Bytes.ends(b"{a}", b"{b}")); rt.put_c(32); rt.put_n(std.Bytes.find(b"{a}", b"{b}")); rt.put_c(32);')
    library_values += [len(a), int(a == b), int(a.startswith(b)), int(a.endswith(b)), a.find(b), len(a.encode()), int(a == b), int(a.startswith(b)), int(a.endswith(b)), a.find(b)]
lines += [
    " churn(300); rt.gc(); rt.put_n(rt.live_objects() - base); rt.put_c(32);",
    ' char* source = "fn f() { return 7; }"; let parsed = run.tokens(source);',
    ' rt.put_n(parsed[0] > 0); rt.put_c(32); rt.put_n(rt.eq_w(source, "fn f() { return 7; }")); rt.put_c(32);',
    ' char* eval_source = "return 42;"; int e = 0;',
    ' while (e < 16) { let q = run.tokens(eval_source); rt.put_n(run.eval(q)); rt.put_c(32); e++; }',
    ' rt.put_n(stable()); rt.put_c(32); rt.put_n(rt.eq_w(eval_source, "return 42;")); rt.put_c(10);',
    " return 0;",
    "}",
]
program = "\n".join(lines) + "\n"
expected = " ".join(str(x) for x in values + library_values + [0, 1, 1, *([42] * 16), 73, 1]) + "\n"


def run(binary):
    result = subprocess.run(binary, input=program, text=True, capture_output=True, timeout=30)
    if result.returncode or result.stdout != expected:
        actual_words = result.stdout.split()
        expected_words = expected.split()
        mismatch = next((i for i, pair in enumerate(zip(actual_words, expected_words)) if pair[0] != pair[1]), min(len(actual_words), len(expected_words)))
        raise SystemExit(
            f"{' '.join(binary)} failed deterministic fuzz seed 0x5a17\n"
            f"exit={result.returncode}, token mismatch at {mismatch}\n"
            f"expected={expected_words[max(0, mismatch - 3):mismatch + 4]!r}\n"
            f"stdout={actual_words[max(0, mismatch - 3):mismatch + 4]!r}\n"
            f"stderr={result.stderr!r}"
        )
    return result.stdout


hosts = [(zy, [zy]), (zym, [zym])]
if js:
    hosts.append(("javascript", ["node", js]))
outputs = [run(command) for _, command in hosts]
if any(output != outputs[0] for output in outputs[1:]):
    raise SystemExit("compiler hosts disagreed on deterministic fuzz output")
print("ok   compiler/runtime/stdlib fuzz: 128 generated expressions, 300 scoped allocations and GC, "
      "16 eval recompiles, unchanged source strings, and 32 randomized Text/Bytes cases on "
      + ", ".join(name for name, _ in hosts))