import base64

from mail_intake.parsers import normalize_subject
from mail_intake.parsers import parse_headers, extract_sender
from mail_intake.parsers import extract_body


def _b64(text: str) -> str:
    return base64.b64encode(text.encode("utf-8")).decode("utf-8")


# --------------------
# Subject parsing
# --------------------

def test_normalize_subject_strips_common_prefixes():
    assert normalize_subject("Re: Interview Update") == "Interview Update"
    assert normalize_subject("Fwd: Re: Offer Letter") == "Offer Letter"
    assert normalize_subject("FW: Re: FW: Status") == "Status"


def test_normalize_subject_preserves_content_and_case():
    subject = "Interview Update – Backend Role"
    assert normalize_subject(subject) == subject


def test_normalize_subject_empty_and_none_safe():
    assert normalize_subject("") == ""


# --------------------
# Header parsing
# --------------------

def test_parse_headers_lowercases_keys():
    raw_headers = [
        {"name": "From", "value": "Alice <alice@example.com>"},
        {"name": "Subject", "value": "Hello"},
    ]

    headers = parse_headers(raw_headers)

    assert headers["from"] == "Alice <alice@example.com>"
    assert headers["subject"] == "Hello"


def test_parse_headers_ignores_invalid_entries():
    raw_headers = [
        {"name": "From", "value": "Bob <bob@example.com>"},
        {"name": None, "value": "X"},
        {"name": "X-Test", "value": None},
    ]

    headers = parse_headers(raw_headers)
    assert "from" in headers
    assert "x-test" not in headers


def test_extract_sender_with_name_and_email():
    headers = {"from": "Alice Smith <alice@example.com>"}
    email, name = extract_sender(headers)

    assert email == "alice@example.com"
    assert name == "Alice Smith"


def test_extract_sender_email_only():
    headers = {"from": "bob@example.com"}
    email, name = extract_sender(headers)

    assert email == "bob@example.com"
    assert name is None


def test_extract_sender_missing_from():
    email, name = extract_sender({})
    assert email == ""
    assert name is None


# --------------------
# Body parsing
# --------------------

def test_extract_body_prefers_text_plain():
    payload = {
        "parts": [
            {
                "mimeType": "text/html",
                "body": {"data": _b64("<p>Hello <b>HTML</b></p>")},
            },
            {
                "mimeType": "text/plain",
                "body": {"data": _b64("Hello TEXT")},
            },
        ]
    }

    body = extract_body(payload)
    assert body == "Hello TEXT"


def test_extract_body_falls_back_to_html():
    payload = {
        "parts": [
            {
                "mimeType": "text/html",
                "body": {"data": _b64("<p>Hello <b>World</b></p>")},
            }
        ]
    }

    body = extract_body(payload)
    assert "Hello" in body
    assert "World" in body


def test_extract_body_single_part():
    payload = {
        "body": {"data": _b64("Single part body")}
    }

    body = extract_body(payload)
    assert body == "Single part body"


def test_extract_body_empty_payload():
    assert extract_body({}) == ""