import os
import subprocess
from pathlib import Path

WORK = Path(os.environ["TB_WORK"])
BASH = os.environ.get("TB_BASH", "bash")
CANON = "./bin/canon"


def run_canon(source, target):
    return subprocess.run(
        [BASH, "-c", 'exec ./bin/canon "$@"', "canon", str(source), str(target)],
        cwd=str(WORK),
        capture_output=True,
        text=True,
        encoding="utf-8",
    )


def case_dir():
    path = Path(os.environ["TB_ROOT"]) / "tmp" / "cases"
    path.mkdir(parents=True, exist_ok=True)
    return path


def write_case(name, body, newline=""):
    path = case_dir() / name
    with open(path, "w", encoding="utf-8", newline=newline) as handle:
        handle.write(body)
    return path


def test_missing_input_exits_2():
    target = case_dir() / "missing.tsv"
    if target.exists():
        target.unlink()
    proc = run_canon("does-not-exist.csv", target)
    assert proc.returncode == 2, proc.stderr
    assert proc.stderr.strip() == "no such file: does-not-exist.csv"
    assert not target.exists(), "output must not be created on error"


def test_duplicate_column_exits_3():
    source = write_case("dup.csv", "id,ID\n1,2\n")
    target = case_dir() / "dup.tsv"
    if target.exists():
        target.unlink()
    proc = run_canon(source, target)
    assert proc.returncode == 3, proc.stderr
    assert proc.stderr.strip() == "duplicate column: ID"
    assert not target.exists()


def test_malformed_row_exits_4_with_physical_line():
    source = write_case("bad.csv", "id,sku\n1,a\n2,b,c\n")
    target = case_dir() / "bad.tsv"
    if target.exists():
        target.unlink()
    proc = run_canon(source, target)
    assert proc.returncode == 4, proc.stderr
    assert proc.stderr.strip() == "malformed row: line 3"
    assert not target.exists()


def test_orders_sample_is_canonicalised():
    target = case_dir() / "orders.tsv"
    proc = run_canon("data/orders.csv", target)
    assert proc.returncode == 0, proc.stderr
    expected = (
        "id\tsku\tqty\tprice\n"
        "1\tSKU-1\t5\t0.75\n"
        "1\tSKU-2\t10\t2\n"
        "2\tSKU-1\t5\t1000\n"
        "3\tSKU-9\t2\t1.5\n"
    )
    assert target.read_bytes() == expected.encode("utf-8")


def test_output_has_no_bom_and_uses_lf():
    target = case_dir() / "orders.tsv"
    run_canon("data/orders.csv", target)
    raw = target.read_bytes()
    assert not raw.startswith(b"\xef\xbb\xbf")
    assert b"\r" not in raw


def test_embedded_newline_survives():
    source = write_case("multi.csv", 'id,note\n2,"line one\nline two"\n1,plain\n')
    target = case_dir() / "multi.tsv"
    proc = run_canon(source, target)
    assert proc.returncode == 0, proc.stderr
    expected = "id\tnote\n1\tplain\n2\tline one\nline two\n"
    assert target.read_bytes() == expected.encode("utf-8")


def test_numeric_normalisation():
    source = write_case(
        "nums.csv", "id,v\n1,+5\n2,007\n3,-0\n4,1.0\n5,2.5e-3\n6,abc\n"
    )
    target = case_dir() / "nums.tsv"
    proc = run_canon(source, target)
    assert proc.returncode == 0, proc.stderr
    expected = "id\tv\n1\t5\n2\t7\n3\t0\n4\t1\n5\t0.0025\n6\tabc\n"
    assert target.read_bytes() == expected.encode("utf-8")


def test_sorting_is_byte_order_not_numeric():
    source = write_case("ids.csv", "id,x\n10,a\n9,b\n")
    target = case_dir() / "ids.tsv"
    proc = run_canon(source, target)
    assert proc.returncode == 0, proc.stderr
    assert target.read_bytes() == b"id\tx\n10\ta\n9\tb\n"