package intelligence

import (
	"strings"
	"testing"
	"time"
)

func day(y int, m time.Month, d int) time.Time { return time.Date(y, m, d, 0, 0, 0, 0, time.UTC) }
func ptr[T any](v T) *T                        { return &v }

// THE WHOLE POINT, as one assertion: two TS/SCI candidates who look identical today are not the same asset,
// and this is where the difference becomes visible.
func TestThreeMonthsOutAndTwentyFiveMonthsOutAreDifferentAnswers(t *testing.T) {
	now := day(2026, time.August, 1)

	fresh := Access(AccessFacts{AccessEndedOn: ptr(day(2026, time.May, 1))}, now)
	stale := Access(AccessFacts{AccessEndedOn: ptr(day(2024, time.July, 1))}, now)

	if fresh.Posture != PostureReinstatable {
		t.Errorf("three months out = %q, want reinstatable", fresh.Posture)
	}
	if stale.Posture != PostureInvestigationLikely {
		t.Errorf("twenty five months out = %q, want investigation_likely", stale.Posture)
	}
	if fresh.Posture == stale.Posture {
		t.Fatal("the two rendered the same, which is the defect this exists to remove")
	}
}

// The boundary itself. Somebody separated on 15 January reaches twenty four months on 15 January two years
// later, and the day before that they are still inside.
func TestTheTwentyFourMonthBoundaryIsExact(t *testing.T) {
	ended := day(2024, time.January, 15)
	for _, c := range []struct {
		name string
		asOf time.Time
		want AccessPosture
	}{
		{"one day before the line", day(2026, time.January, 14), PostureClosing},
		{"on the line", day(2026, time.January, 15), PostureClosing},
		{"one day past", day(2026, time.January, 16), PostureInvestigationLikely},
	} {
		got := Access(AccessFacts{AccessEndedOn: &ended}, c.asOf).Posture
		if got != c.want {
			t.Errorf("%s: posture = %q, want %q", c.name, got, c.want)
		}
	}
}

// A stale adjudication fails the rule ON ITS OWN, and the message has to say which bound failed. A recruiter
// told "past twenty four months" about somebody eight months out would go looking for the wrong thing.
func TestAStaleAdjudicationFailsIndependentlyOfTheClock(t *testing.T) {
	now := day(2026, time.August, 1)
	got := Access(AccessFacts{
		AccessEndedOn:   ptr(day(2025, time.December, 1)), // eight months, well inside the window
		LastAdjudicated: ptr(day(2019, time.January, 1)),  // but seven years ago
	}, now)

	if got.Posture != PostureInvestigationLikely {
		t.Fatalf("posture = %q, want investigation_likely on a stale adjudication", got.Posture)
	}
	if !got.AdjudicationStale {
		t.Error("the adjudication bound failed and the answer does not say so")
	}
	if !strings.Contains(got.Detail, "adjudication") {
		t.Errorf("the detail does not name the reason: %q", got.Detail)
	}
}

// In access beats everything. Somebody currently sponsored has no window running at all.
func TestInAccessHasNoWindow(t *testing.T) {
	got := Access(AccessFacts{CVEnrolled: ptr(true)}, day(2026, time.August, 1))
	if got.Posture != PostureInAccess {
		t.Fatalf("posture = %q, want in_access", got.Posture)
	}
	if got.DaysLeftInWindow != nil || got.MonthsOutOfAccess != nil {
		t.Error("a window was computed for somebody who is in access")
	}
}

// UNKNOWN IS NOT A PROBLEM AND MUST NOT READ AS ONE. Most benches start with no access history recorded, and
// a product that painted every one of them as a risk would be crying wolf on its entire dataset.
func TestUnknownSaysTheRecordIsIncompleteNotThatTheCandidateIsRisky(t *testing.T) {
	got := Access(AccessFacts{}, day(2026, time.August, 1))
	if got.Posture != PostureUnknown {
		t.Fatalf("posture = %q, want unknown", got.Posture)
	}
	if !strings.Contains(got.Detail, "gap in the record") {
		t.Errorf("the detail blames the candidate rather than the record: %q", got.Detail)
	}
	if got.MonthsOutOfAccess != nil {
		t.Error("months were computed from a date that does not exist")
	}
}

// CALENDAR MONTHS, NOT THIRTY DAY BLOCKS. Dividing days by 30.44 is wrong by the better part of a week at the
// twenty four month mark, which is precisely where it decides the answer.
func TestMonthsAreCalendarMonths(t *testing.T) {
	for _, c := range []struct {
		from, to time.Time
		want     int
	}{
		{day(2024, time.January, 31), day(2024, time.February, 29), 0}, // not yet a full month
		{day(2024, time.January, 15), day(2024, time.February, 15), 1},
		{day(2024, time.January, 15), day(2026, time.January, 14), 23},
		{day(2024, time.January, 15), day(2026, time.January, 15), 24},
	} {
		if got := monthsBetween(c.from, c.to); got != c.want {
			t.Errorf("monthsBetween(%s, %s) = %d, want %d",
				c.from.Format("2006-01-02"), c.to.Format("2006-01-02"), got, c.want)
		}
	}
}