import sqlite3
import os
import shutil
from pathlib import Path

import pytest

from fin_hub.services.evaluate import evaluate_runway
from fin_hub.services.evidence import build_runway_report, seed_fixture_ledger, write_runway_evidence
from fin_hub.services.ledger import (
    client_margin_report,
    import_csv,
    monthly_burn_series,
    monthly_summary,
    record_engagement_price,
    reverse_financial_fact,
    set_opening_balance,
)

FIXTURES = Path(__file__).parent / "fixtures"


def test_ledger_import_anthropic_cost_only_does_not_require_tokens(tmp_path: Path):
    ledger = tmp_path / "ledger.db"
    source = tmp_path / "anthropic-cost-only.csv"
    source.write_text(
        "model,cost,currency,usage_date\nclaude-opus-4-20250514,20.00,USD,2026-08-01\n",
        encoding="utf-8",
    )
    result = import_csv(source, "anthropic", ledger_path=ledger)
    assert result.rows_imported == 1
    rollups = monthly_summary(ledger_path=ledger)
    assert rollups[0].currency == "USD"
    assert rollups[0].total == pytest.approx(20.0)


def test_ledger_import_and_monthly_summary(tmp_path: Path):
    ledger = tmp_path / "ledger.db"
    set_opening_balance(ledger, 12000.0)

    cloud = import_csv(FIXTURES / "cloud-costs.csv", "cloud", ledger_path=ledger)
    host = import_csv(FIXTURES / "hosteurope.csv", "hosteurope", ledger_path=ledger)

    assert cloud.rows_imported == 3
    assert host.rows_imported == 2

    rollups = monthly_summary(ledger_path=ledger)
    eur_totals = {rollup.period_month: rollup.total for rollup in rollups if rollup.currency == "EUR"}
    assert eur_totals["2026-06"] == pytest.approx(85.5 + 99.8)

    burns = monthly_burn_series(ledger_path=ledger, currency="EUR")
    assert burns == [pytest.approx(185.3)]


def test_ledger_import_skips_unchanged_file(tmp_path: Path):
    ledger = tmp_path / "ledger.db"
    first = import_csv(FIXTURES / "cloud-costs.csv", "cloud", ledger_path=ledger)
    second = import_csv(FIXTURES / "cloud-costs.csv", "cloud", ledger_path=ledger)
    assert first.rows_imported == 3
    assert second.skipped is True
    assert second.rows_imported == 0


def test_ledger_import_is_idempotent_when_file_is_renamed_or_touched(tmp_path: Path):
    ledger = tmp_path / "ledger.db"
    source = tmp_path / "costs.csv"
    shutil.copy(FIXTURES / "cloud-costs.csv", source)
    renamed = tmp_path / "renamed.csv"

    first = import_csv(source, "cloud", ledger_path=ledger)
    os.utime(source, (source.stat().st_atime, source.stat().st_mtime + 1))
    touched = import_csv(source, "cloud", ledger_path=ledger)
    shutil.copy(source, renamed)
    delivered_again = import_csv(renamed, "cloud", ledger_path=ledger)

    assert first.rows_imported == 3
    assert touched.rows_imported == 0
    assert delivered_again.rows_imported == 0
    assert monthly_summary(ledger_path=ledger)[0].entry_count == 3


def test_changed_fact_requires_and_applies_one_correction(tmp_path: Path):
    ledger = tmp_path / "ledger.db"
    source = tmp_path / "costs.csv"
    source.write_text(
        "service,amount,currency,period_month\ncompute,10.00,EUR,2026-07\n",
        encoding="utf-8",
    )
    import_csv(source, "cloud", ledger_path=ledger)
    source.write_text(
        "service,amount,currency,period_month\ncompute,12.00,EUR,2026-07\n",
        encoding="utf-8",
    )

    with pytest.raises(ValueError, match="explicit correction"):
        import_csv(source, "cloud", ledger_path=ledger)
    corrected = import_csv(source, "cloud", ledger_path=ledger, force=True)
    duplicate = import_csv(source, "cloud", ledger_path=ledger, force=True)

    assert corrected.rows_imported == 1
    assert duplicate.rows_imported == 0
    rollup = monthly_summary(ledger_path=ledger)[0]
    assert rollup.total == 12.0
    assert rollup.entry_count == 1
    with sqlite3.connect(ledger) as conn:
        facts = conn.execute(
            "SELECT correction_of, is_current FROM ledger_entries ORDER BY id"
        ).fetchall()
    assert facts[0][1] == 0
    assert facts[1][0] is not None
    assert facts[1][1] == 1


def test_financial_fact_reversal_is_append_only_and_zeroes_effective_total(tmp_path: Path):
    ledger = tmp_path / "ledger.db"
    source = tmp_path / "costs.csv"
    source.write_text(
        "service,amount,currency,period_month\ncompute,10.00,EUR,2026-07\n",
        encoding="utf-8",
    )
    import_csv(source, "cloud", ledger_path=ledger)
    with sqlite3.connect(ledger) as conn:
        fact_id = conn.execute(
            "SELECT financial_fact_id FROM ledger_entries"
        ).fetchone()[0]

    reversal_id = reverse_financial_fact(
        fact_id, source="provider-credit-note", ledger_path=ledger
    )

    rollup = monthly_summary(ledger_path=ledger)[0]
    assert rollup.total == 0.0
    with sqlite3.connect(ledger) as conn:
        rows = conn.execute(
            "SELECT financial_fact_id, correction_of, adjustment_kind, is_current "
            "FROM ledger_entries ORDER BY id"
        ).fetchall()
    assert rows == [
        (fact_id, None, "charge", 0),
        (reversal_id, fact_id, "reversal", 1),
    ]


def test_ledger_import_preserves_client_attribution(tmp_path: Path):
    source = tmp_path / "attributed.csv"
    source.write_text(
        "product,amount,currency,invoice_date,client_id,application_id,app_instance_id\n"
        "Managed cluster,42.00,EUR,2026-07-01,acme,portal,prod-01\n",
        encoding="utf-8",
    )
    ledger = tmp_path / "ledger.db"

    import_csv(source, "hosteurope", ledger_path=ledger)

    with sqlite3.connect(ledger) as conn:
        row = conn.execute(
            "SELECT client_id, application_id, app_instance_id, cost_attribution_key "
            "FROM ledger_entries"
        ).fetchone()
    assert row == (
        "acme",
        "portal",
        "prod-01",
        "client:acme|app:portal|instance:prod-01",
    )


def test_existing_ledger_schema_is_migrated_additively(tmp_path: Path):
    ledger = tmp_path / "legacy.db"
    with sqlite3.connect(ledger) as conn:
        conn.execute(
            "CREATE TABLE ledger_entries ("
            "id INTEGER PRIMARY KEY, source_type TEXT NOT NULL, category TEXT NOT NULL, "
            "label TEXT NOT NULL, amount REAL NOT NULL, currency TEXT NOT NULL, "
            "period_month TEXT NOT NULL, incurred_on TEXT, source_path TEXT NOT NULL, "
            "imported_at TEXT NOT NULL)"
        )

    monthly_summary(ledger_path=ledger)

    with sqlite3.connect(ledger) as conn:
        columns = {row[1] for row in conn.execute("PRAGMA table_info(ledger_entries)")}
    assert {
        "client_id",
        "application_id",
        "app_instance_id",
        "cost_attribution_key",
    }.issubset(columns)


def test_engagement_price_and_margin_report(tmp_path: Path):
    source = tmp_path / "attributed.csv"
    source.write_text(
        "product,amount,currency,invoice_date,client_id,application_id,app_instance_id\n"
        "Managed cluster,42.00,EUR,2026-07-01,acme,portal,prod-01\n",
        encoding="utf-8",
    )
    ledger = tmp_path / "ledger.db"
    import_csv(source, "hosteurope", ledger_path=ledger)
    price = record_engagement_price(
        client_id="acme",
        application_id="portal",
        app_instance_id="prod-01",
        period_month="2026-07",
        amount=100.0,
        currency="eur",
        source="agreement-2026-01",
        ledger_path=ledger,
    )

    margins = client_margin_report(ledger_path=ledger)

    assert margins[0].price_id == price.id
    assert margins[0].revenue == 100.0
    assert margins[0].attributed_cost == 42.0
    assert margins[0].margin == 58.0
    assert margins[0].currency == "EUR"


def test_engagement_price_revision_supersedes_prior_price(tmp_path: Path):
    ledger = tmp_path / "ledger.db"
    original = record_engagement_price(
        client_id="acme",
        application_id="portal",
        app_instance_id="prod-01",
        period_month="2026-07",
        amount=100.0,
        currency="EUR",
        source="agreement-v1",
        ledger_path=ledger,
    )
    revision = record_engagement_price(
        client_id="acme",
        application_id="portal",
        app_instance_id="prod-01",
        period_month="2026-07",
        amount=120.0,
        currency="EUR",
        source="agreement-v2",
        revision_of=original.id,
        ledger_path=ledger,
    )

    margins = client_margin_report(ledger_path=ledger)

    assert [(row.price_id, row.revenue) for row in margins] == [(revision.id, 120.0)]


def test_engagement_price_requires_explicit_revision(tmp_path: Path):
    ledger = tmp_path / "ledger.db"
    kwargs = {
        "client_id": "acme",
        "application_id": "portal",
        "app_instance_id": "prod-01",
        "period_month": "2026-07",
        "amount": 100.0,
        "currency": "EUR",
        "source": "agreement",
        "ledger_path": ledger,
    }
    original = record_engagement_price(**kwargs)

    with pytest.raises(ValueError, match=original.id):
        record_engagement_price(**kwargs)


def test_margin_does_not_join_cost_in_another_currency(tmp_path: Path):
    source = tmp_path / "attributed.csv"
    source.write_text(
        "product,amount,currency,invoice_date,client_id,application_id,app_instance_id\n"
        "Managed cluster,42.00,USD,2026-07-01,acme,portal,prod-01\n",
        encoding="utf-8",
    )
    ledger = tmp_path / "ledger.db"
    import_csv(source, "hosteurope", ledger_path=ledger)
    record_engagement_price(
        client_id="acme",
        application_id="portal",
        app_instance_id="prod-01",
        period_month="2026-07",
        amount=100.0,
        currency="EUR",
        source="agreement",
        ledger_path=ledger,
    )

    margin = client_margin_report(ledger_path=ledger)[0]
    assert margin.attributed_cost == 0.0
    assert margin.margin == 100.0


def test_evaluate_runway_from_ledger(tmp_path: Path):
    ledger = tmp_path / "ledger.db"
    seed_fixture_ledger(ledger_path=ledger, opening_balance=12000.0)
    report = evaluate_runway(ledger_path=ledger, alert_threshold_months=3.0)
    assert report["runway"]["current_balance"] == 12000.0
    assert report["runway"]["monthly_burn"] > 0


def test_build_runway_report_and_write_evidence(tmp_path: Path):
    ledger = tmp_path / "ledger.db"
    seed_fixture_ledger(ledger_path=ledger, opening_balance=12000.0)
    text = build_runway_report(ledger_path=ledger)
    assert "Runway Dogfood Evidence" in text
    assert "2026-06" in text

    output = write_runway_evidence(
        ledger_path=ledger,
        output_dir=tmp_path / "evidence",
        opening_balance=12000.0,
    )
    assert output.exists()
    assert "runway-dogfood-" in output.name