"""Tests for app.services.csv_import.

Uses the real T212 pie-export sample at tests/fixtures/t212_pie_export.csv
for the happy path, then synthetic fixtures for edge cases.
"""
from __future__ import annotations

from pathlib import Path

import pytest

from app.services.csv_import import (
    CSVImportError,
    ParsedPie,
    ParsedPosition,
    parse_t212_csv,
)


FIXTURE = Path(__file__).parent / "fixtures" / "t212_pie_export.csv"


# --- Happy path: real T212 export ------------------------------------------


def test_parses_real_t212_export():
    pie = parse_t212_csv(FIXTURE.read_bytes())
    assert isinstance(pie, ParsedPie)
    assert pie.name == "Defensive Ex-US 2026"
    assert pie.invested == pytest.approx(11616.75)
    assert pie.value == pytest.approx(11619.33)
    assert pie.result == pytest.approx(2.58)
    assert len(pie.positions) == 13


def test_first_position_fields_resolved():
    pie = parse_t212_csv(FIXTURE.read_bytes())
    sgln = next(p for p in pie.positions if p.slice == "SGLN")
    assert sgln.name == "iShares Physical Gold"
    assert sgln.invested_value == pytest.approx(2325)
    assert sgln.current_value == pytest.approx(2324.3)
    assert sgln.result == pytest.approx(-0.7)
    assert sgln.quantity == pytest.approx(35.12084592)
    assert sgln.dividends_gained is None  # 'N/A' in source
    assert sgln.average_price == pytest.approx(2325 / 35.12084592)
    assert sgln.current_price == pytest.approx(2324.3 / 35.12084592)


def test_total_row_excluded_from_positions():
    pie = parse_t212_csv(FIXTURE.read_bytes())
    assert not any(p.slice.lower() == "total" for p in pie.positions)


# --- Edge cases: defensive parsing -----------------------------------------


def test_empty_file_raises():
    with pytest.raises(CSVImportError, match="Empty"):
        parse_t212_csv("")


def test_missing_required_column_raises():
    # Only Name, no Slice or quantity
    csv = '"Name","Value"\n"iShares","100"\n'
    with pytest.raises(CSVImportError, match="missing required column"):
        parse_t212_csv(csv)


def test_no_position_rows_raises():
    # Headers present but only the Total aggregate row.
    csv = (
        '"Slice","Name","Invested value","Value","Result","Owned quantity"\n'
        '"Total","Empty Pie",0,0,0,"-"\n'
    )
    with pytest.raises(CSVImportError, match="no parseable position"):
        parse_t212_csv(csv)


def test_reordered_columns():
    """T212 sometimes re-orders columns between exports. Header-name matching
    has to make that a non-issue."""
    csv = (
        '"Name","Owned quantity","Slice","Value","Invested value","Result"\n'
        '"Shell","10.5","SHEL","350","340","10"\n'
        '"Total","-","Total","350","340","10"\n'
    )
    pie = parse_t212_csv(csv)
    assert len(pie.positions) == 1
    p = pie.positions[0]
    assert p.slice == "SHEL"
    assert p.name == "Shell"
    assert p.quantity == pytest.approx(10.5)
    assert p.invested_value == pytest.approx(340)


def test_unknown_columns_silently_ignored():
    csv = (
        '"Slice","Name","Owned quantity","Invested value",'
        '"Something T212 added later","Value"\n'
        '"SHEL","Shell","10","100","ignore me","105"\n'
        '"Total","-","-","100","-","105"\n'
    )
    pie = parse_t212_csv(csv)
    assert pie.positions[0].slice == "SHEL"
    assert pie.positions[0].current_value == pytest.approx(105)


def test_handles_utf8_bom():
    """Excel-saved CSVs often have a UTF-8 BOM. Should not break header
    matching for the first column."""
    csv = (
        ""
        '"Slice","Name","Invested value","Value","Result","Owned quantity"\n'
        '"SHEL","Shell",100,105,5,"10"\n'
        '"Total","Test",100,105,5,"-"\n'
    ).encode("utf-8")
    pie = parse_t212_csv(csv)
    assert pie.positions[0].slice == "SHEL"
    assert pie.name == "Test"


def test_dash_and_na_become_none():
    csv = (
        '"Slice","Name","Invested value","Value","Result","Owned quantity",'
        '"Dividends gained","Dividends cash","Dividends reinvested"\n'
        '"SHEL","Shell",100,"-",,"10","N/A","—","n/a"\n'
        '"Total","P",100,100,0,"-","0","0","0"\n'
    )
    pie = parse_t212_csv(csv)
    p = pie.positions[0]
    assert p.current_value is None
    assert p.result is None
    assert p.dividends_gained is None
    assert p.dividends_cash is None
    assert p.dividends_reinvested is None


def test_thousand_separator_commas_tolerated():
    csv = (
        '"Slice","Name","Invested value","Value","Result","Owned quantity"\n'
        '"BIG","Mega Holding","1,234,567.89","1,250,000",15432.11,"100"\n'
        '"Total","Big Pie","1,234,567.89","1,250,000",15432.11,"-"\n'
    )
    pie = parse_t212_csv(csv)
    assert pie.positions[0].invested_value == pytest.approx(1234567.89)
    assert pie.invested == pytest.approx(1234567.89)


def test_blank_rows_skipped():
    csv = (
        '"Slice","Name","Invested value","Value","Result","Owned quantity"\n'
        '\n'
        '"SHEL","Shell",100,105,5,"10"\n'
        '   \n'
        '"Total","P",100,105,5,"-"\n'
    )
    pie = parse_t212_csv(csv)
    assert len(pie.positions) == 1


def test_zero_quantity_skipped():
    """A position row with quantity=0 isn't a real holding — likely a stub
    left over from a fully-sold position. Don't fail; skip."""
    csv = (
        '"Slice","Name","Invested value","Value","Result","Owned quantity"\n'
        '"GONE","Sold Out",0,0,0,"0"\n'
        '"SHEL","Shell",100,105,5,"10"\n'
        '"Total","P",100,105,5,"-"\n'
    )
    pie = parse_t212_csv(csv)
    assert [p.slice for p in pie.positions] == ["SHEL"]


def test_position_without_total_row_still_parses():
    csv = (
        '"Slice","Name","Invested value","Value","Result","Owned quantity"\n'
        '"SHEL","Shell",100,105,5,"10"\n'
    )
    pie = parse_t212_csv(csv)
    assert len(pie.positions) == 1
    assert pie.name is None
    assert pie.invested is None