package autocall

import (
	"fmt"
	"testing"
	"time"
)

const me = "F4BPO"

// base is a slot boundary, so slot parity in the tests is the real arithmetic.
var base = time.Date(2026, 9, 6, 12, 0, 0, 0, time.UTC)

func at(period int) time.Time { return base.Add(time.Duration(period) * 15 * time.Second) }

func cq(call string, need Need, snr int, opts ...func(*Candidate)) Candidate {
	c := Candidate{
		Decode: Decode{Call: call, Band: "20m", Mode: "FT8", SNR: snr, CQ: true,
			Msg: "CQ " + call + " JN36", TRPeriod: 15, IsNew: true},
		Need: need,
	}
	for _, o := range opts {
		o(&c)
	}
	return c
}

func watched(c *Candidate) { c.Watched = true }
func worked(c *Candidate)  { c.Worked = true }

// busy is a station in the middle of an exchange with somebody else.
func busy(call string, need Need, snr int) Candidate {
	c := cq(call, need, snr)
	c.CQ = false
	c.Msg = "VP6D " + call + " JN36"
	return c
}

// callsMe is a station answering us.
func callsMe(call string, need Need, snr int) Candidate {
	c := cq(call, need, snr)
	c.CQ = false
	c.Msg = me + " " + call + " -12"
	return c
}

func period(n int, decodes ...Candidate) Period {
	for i := range decodes {
		decodes[i].At = at(n)
	}
	return Period{Key: fmt.Sprintf("p%d", n), At: at(n), TRPeriod: 15, Decodes: decodes, MyCall: me}
}

func on() *Engine { return New(Settings{Enabled: true}) }

// ── The ladder ────────────────────────────────────────────────────────────

func TestLadderOrder(t *testing.T) {
	// Every rung, in the order the operator asked for.
	order := []Candidate{
		cq("A", NeedDXCC, 0, watched), cq("B", NeedDXCC, 0),
		cq("C", NeedBand, 0, watched), cq("D", NeedBand, 0),
		cq("E", NeedMode, 0, watched), cq("F", NeedMode, 0),
		cq("G", NeedSlot, 0, watched), cq("H", NeedSlot, 0),
		cq("I", NeedNone, 0, watched),
	}
	for i := 1; i < len(order); i++ {
		if rank(order[i-1]) <= rank(order[i]) {
			t.Errorf("%s (%d) does not outrank %s (%d)",
				order[i-1].Call, rank(order[i-1]), order[i].Call, rank(order[i]))
		}
	}
	// A station with nothing needed and not watched is not called at all.
	if rank(cq("Z", NeedNone, 0)) != 0 {
		t.Error("a station with nothing to gain from it ranks above zero")
	}
	// And the pick agrees with the ladder, whatever order the period lists them.
	e := on()
	a := e.OnPeriod(period(0, order[7], order[3], order[0], order[5]))
	if a.Kind != DoReply || a.Decode.Call != "A" {
		t.Fatalf("picked %+v, want the watched new entity", a)
	}
}

func TestStrongestWinsBetweenEquals(t *testing.T) {
	e := on()
	a := e.OnPeriod(period(0, cq("WEAK", NeedBand, -20), cq("LOUD", NeedBand, -5)))
	if a.Decode.Call != "LOUD" {
		t.Errorf("picked %q, want the strongest of two equal needs", a.Decode.Call)
	}
}

// ── The busy station ──────────────────────────────────────────────────────

func TestBusyStationIsNeverCalled(t *testing.T) {
	e := on()
	// The new entity is answering a DXpedition; the new band is calling CQ.
	a := e.OnPeriod(period(0, busy("RARE", NeedDXCC, -3), cq("DL1XX", NeedBand, -15)))
	if a.Kind != DoReply || a.Decode.Call != "DL1XX" {
		t.Fatalf("called %+v — a station in mid-QSO cannot answer and must not be called", a)
	}
	// It is not banned: the moment it calls CQ it takes the slot back, once the
	// QSO in hand is over.
	e2 := on()
	if a := e2.OnPeriod(period(0, cq("RARE", NeedDXCC, -3))); a.Decode.Call != "RARE" {
		t.Errorf("the same station calling CQ was not called: %+v", a)
	}
}

func TestFinalFrameIsCallable(t *testing.T) {
	e := on()
	c := busy("RARE", NeedDXCC, -3)
	c.Msg = "IK2AAA RARE RR73" // one frame from being free
	if a := e.OnPeriod(period(0, c)); a.Kind != DoReply {
		t.Errorf("a station sending its last frame is free next period: %+v", a)
	}
}

// ── The brakes ────────────────────────────────────────────────────────────

func TestAttemptsCapAtSevenAndFifteen(t *testing.T) {
	for _, tc := range []struct {
		name string
		opt  func(*Candidate)
		want int
	}{{"plain", func(*Candidate) {}, 7}, {"watched", watched, 15}} {
		e := on()
		e.OnPeriod(period(0, cq("DX", NeedDXCC, -5, tc.opt)))
		tx := TXState{Transmitting: true, Msg: "DX " + me + " JN36"}
		for i := 1; i < tc.want; i++ {
			if a := e.NoteTX(tx); a.Kind != DoNothing {
				t.Fatalf("%s: gave up at call %d of %d", tc.name, i, tc.want)
			}
		}
		a := e.NoteTX(tx)
		if a.Kind != DoHalt {
			t.Errorf("%s: still calling after %d attempts", tc.name, tc.want)
		}
		if e.Target() != "" {
			t.Errorf("%s: target still held after giving up", tc.name)
		}
	}
}

func TestOnlyFreshCallsCount(t *testing.T) {
	e := on()
	e.OnPeriod(period(0, cq("DX", NeedDXCC, -5)))
	// The rest of the exchange is not a call: without this the seven were spent
	// on one QSO in progress.
	for _, msg := range []string{"DX " + me + " -12", "DX " + me + " R-12", "DX " + me + " RR73"} {
		if a := e.NoteTX(TXState{Transmitting: true, Msg: msg}); a.Kind != DoNothing {
			t.Fatalf("%q ended the series", msg)
		}
	}
	if e.Status().Attempts != 0 {
		t.Errorf("attempts = %d after three QSO frames, want 0", e.Status().Attempts)
	}
	// A transmission aimed at somebody else counts for nothing either.
	e.NoteTX(TXState{Transmitting: true, Msg: "OTHER " + me + " JN36"})
	if e.Status().Attempts != 0 {
		t.Errorf("a call to another station was counted against the target")
	}
}

func TestMissesOnlyCountTheStationsOwnPeriods(t *testing.T) {
	e := on()
	e.OnPeriod(period(0, cq("DX", NeedDXCC, -5))) // learns nothing yet
	e.OnPeriod(period(2, cq("DX", NeedDXCC, -5))) // seen: it transmits on even periods
	// Its listening periods say nothing about it. Ten of them must not add up
	// to a give-up.
	for _, p := range []int{3, 5, 7, 9, 11} {
		if a := e.OnPeriod(period(p)); a.Kind != DoNothing {
			t.Fatalf("gave up during the station's own listening period %d", p)
		}
	}
	if e.Status().Misses != 0 {
		t.Errorf("misses = %d over five listening periods, want 0", e.Status().Misses)
	}
	// Absent from two of its transmit periods: still holding.
	e.OnPeriod(period(4))
	e.OnPeriod(period(6))
	if e.Target() == "" {
		t.Fatal("gave up after two misses, the limit is three")
	}
	if a := e.OnPeriod(period(8)); a.Kind != DoHalt {
		t.Errorf("still holding after three missed transmit periods: %+v", a)
	}
}

func TestOneMissPerPeriodEvenIfTheHandlerRunsTwice(t *testing.T) {
	e := on()
	e.OnPeriod(period(0, cq("DX", NeedDXCC, -5)))
	e.OnPeriod(period(2, cq("DX", NeedDXCC, -5)))
	p := period(4)
	e.OnPeriod(p)
	e.OnPeriod(p)
	e.OnPeriod(p)
	if e.Status().Misses != 1 {
		t.Errorf("misses = %d after one period handled three times, want 1", e.Status().Misses)
	}
}

func TestClockBackstopReleasesAStuckTarget(t *testing.T) {
	e := on()
	e.OnPeriod(period(0, cq("DX", NeedDXCC, -5)))
	// Decoded every one of its periods and never answering, with the decoder
	// never reporting a transmission: no counter can advance.
	for p := 2; p <= 16; p += 2 {
		e.OnPeriod(period(p, cq("DX", NeedDXCC, -5)))
	}
	if a := e.OnPeriod(period(18, cq("DX", NeedDXCC, -5))); a.Kind != DoHalt {
		t.Errorf("a target held past MaxHold with no counter moving was never released: %+v", a)
	}
}

// ── After a series ────────────────────────────────────────────────────────

func TestAReleasedStationYieldsToAnythingBetter(t *testing.T) {
	e := on()
	e.OnPeriod(period(0, cq("DX", NeedBand, -5)))
	tx := TXState{Transmitting: true, Msg: "DX " + me + " JN36"}
	for i := 0; i < 7; i++ {
		e.NoteTX(tx)
	}
	if e.Target() != "" {
		t.Fatal("still holding after seven calls")
	}
	// It is still there, and so is a new entity: the entity takes the slot.
	a := e.OnPeriod(period(2, cq("DX", NeedBand, -5), cq("RARE", NeedDXCC, -20)))
	if a.Decode.Call != "RARE" {
		t.Errorf("picked %q, want the higher priority over the station just released", a.Decode.Call)
	}
}

func TestAReleasedStationIsCalledAgainWhenNothingBetterIsOnTheAir(t *testing.T) {
	e := on()
	e.OnPeriod(period(0, cq("DX", NeedBand, -5)))
	tx := TXState{Transmitting: true, Msg: "DX " + me + " JN36"}
	for i := 0; i < 7; i++ {
		e.NoteTX(tx)
	}
	a := e.OnPeriod(period(2, cq("DX", NeedBand, -5)))
	if a.Kind != DoReply || a.Decode.Call != "DX" {
		t.Errorf("nothing better on the air and the station was not called again: %+v", a)
	}
}

func TestAStationIsParkedAfterItsRounds(t *testing.T) {
	e := on()
	tx := TXState{Transmitting: true, Msg: "DX " + me + " JN36"}
	for round := 1; round <= 3; round++ {
		a := e.OnPeriod(period(round*2, cq("DX", NeedBand, -5)))
		if a.Kind != DoReply {
			t.Fatalf("round %d: not called (%+v)", round, a)
		}
		for i := 0; i < 7; i++ {
			e.NoteTX(tx)
		}
	}
	// Three series of seven is twenty-one calls. That is the end of it for this
	// session — the whole point of the exercise is that it cannot reach fifty.
	if a := e.OnPeriod(period(20, cq("DX", NeedBand, -5))); a.Kind != DoNothing {
		t.Errorf("a fourth series was started: %+v", a)
	}
}

// ── Handing over ──────────────────────────────────────────────────────────

func TestFinishedQSOMovesToTheNextPriority(t *testing.T) {
	e := on()
	e.OnPeriod(period(0, cq("DX", NeedDXCC, -5)))
	done := callsMe("DX", NeedDXCC, -5)
	done.Msg = me + " DX RR73"
	a := e.OnPeriod(period(2, done, cq("NEXT", NeedBand, -10)))
	if a.Kind != DoReply || a.Decode.Call != "NEXT" {
		t.Errorf("after the QSO ended: %+v, want the next priority in the same period", a)
	}
}

func TestFinishedQSOWithNoPriorityAnswersWhoeverIsCallingUs(t *testing.T) {
	e := on()
	e.OnPeriod(period(0, cq("DX", NeedDXCC, -5)))
	done := callsMe("DX", NeedDXCC, -5)
	done.Msg = me + " DX RR73"
	// Two stations calling us, nothing needed from either: the strongest wins.
	weak := callsMe("WEAK", NeedNone, -18)
	weak.Watched = true
	loud := callsMe("LOUD", NeedNone, -4)
	loud.Watched = true
	a := e.OnPeriod(period(2, done, weak, loud))
	if a.Kind != DoReply || a.Decode.Call != "LOUD" {
		t.Errorf("answered %+v, want the strongest of the stations calling us", a)
	}
}

func TestAlreadyWorkedIsNeverCalled(t *testing.T) {
	e := on()
	a := e.OnPeriod(period(0, cq("DX", NeedDXCC, -5, worked)))
	if a.Kind != DoNothing {
		t.Errorf("called a station already in the log on this band and mode: %+v", a)
	}
}

func TestReplayedHistoryIsNeverCalled(t *testing.T) {
	e := on()
	old := cq("DX", NeedDXCC, -5)
	old.IsNew = false
	if a := e.OnPeriod(period(0, old)); a.Kind != DoNothing {
		t.Errorf("answered a replayed decode: %+v", a)
	}
}

func TestNoCallStartsOverATransmissionInProgress(t *testing.T) {
	e := on()
	p := period(0, cq("DX", NeedDXCC, -5))
	p.TX = TXState{Transmitting: true}
	if a := e.OnPeriod(p); a.Kind != DoNothing {
		t.Errorf("started a call while the decoder was transmitting: %+v", a)
	}
}

// ── The "call this station" field ─────────────────────────────────────────

func TestOnlyCallsThatStation(t *testing.T) {
	e := New(Settings{Enabled: true, Only: "VP6D"})
	a := e.OnPeriod(period(0, cq("RARE", NeedDXCC, -5), cq("VP6D", NeedSlot, -20)))
	if a.Kind != DoReply || a.Decode.Call != "VP6D" {
		t.Fatalf("picked %+v, want the station named in the field", a)
	}
	// Same brakes, then a hard stop: there is nothing else it was asked to do.
	tx := TXState{Transmitting: true, Msg: "VP6D " + me + " JN36"}
	for i := 0; i < 7; i++ {
		e.NoteTX(tx)
	}
	if !e.Status().Stopped {
		t.Error("an explicit target ran out of attempts and the feature did not stop")
	}
	if a := e.OnPeriod(period(2, cq("VP6D", NeedSlot, -20))); a.Kind != DoNothing {
		t.Errorf("kept calling after the stop: %+v", a)
	}
	e.Reset()
	if a := e.OnPeriod(period(4, cq("VP6D", NeedSlot, -20))); a.Kind != DoReply {
		t.Errorf("the operator restarted it and nothing happened: %+v", a)
	}
}

func TestDisabledDoesNothingAtAll(t *testing.T) {
	e := New(Settings{})
	if a := e.OnPeriod(period(0, cq("DX", NeedDXCC, 0))); a.Kind != DoNothing {
		t.Errorf("switched off and still calling: %+v", a)
	}
	if a := e.NoteTX(TXState{Transmitting: true, Msg: "DX " + me + " JN36"}); a.Kind != DoNothing {
		t.Errorf("switched off and still counting: %+v", a)
	}
}

func TestOnlyStopsOnceThatStationIsWorked(t *testing.T) {
	e := New(Settings{Enabled: true, Only: "VP6D"})
	e.OnPeriod(period(0, cq("VP6D", NeedDXCC, -10)))
	done := callsMe("VP6D", NeedDXCC, -10)
	done.Msg = me + " VP6D RR73"
	e.OnPeriod(period(2, done))
	// The station is still on the air calling CQ. It has been worked: an
	// explicit request is for one QSO, not for the whole evening.
	if a := e.OnPeriod(period(4, cq("VP6D", NeedDXCC, -10))); a.Kind != DoNothing {
		t.Errorf("called the named station again after working it: %+v", a)
	}
}

func TestAStationJustWorkedIsNotCalledBackWhileTheLogCatchesUp(t *testing.T) {
	e := on()
	e.OnPeriod(period(0, cq("DX", NeedDXCC, -5)))
	done := callsMe("DX", NeedDXCC, -5)
	done.Msg = me + " DX RR73"
	e.OnPeriod(period(2, done))
	// Still flagged as a new entity — the QSO is not in the log yet — and still
	// calling CQ. It must not be answered again.
	if a := e.OnPeriod(period(4, cq("DX", NeedDXCC, -5))); a.Kind != DoNothing {
		t.Errorf("called back a station worked two periods ago: %+v", a)
	}
}

func TestChaseListTakesSeveralCallsigns(t *testing.T) {
	// Typed the way an operator types a list: commas, spaces, or both.
	for _, field := range []string{"VP6D 3Y0J", "vp6d,3y0j", "VP6D, 3Y0J", " VP6D ;3Y0J "} {
		if got := onlyList(field); len(got) != 2 || got[0] != "VP6D" || got[1] != "3Y0J" {
			t.Errorf("%q parsed as %v, want [VP6D 3Y0J]", field, got)
		}
	}

	e := New(Settings{Enabled: true, Only: "VP6D, 3Y0J"})
	// Nothing off the list is called, however rare it is.
	if a := e.OnPeriod(period(0, cq("RARE", NeedDXCC, -1))); a.Kind != DoNothing {
		t.Errorf("called a station that is not on the chase list: %+v", a)
	}
	// Between two listed stations the ladder still decides: the new entity over
	// the new slot, whatever their order in the period.
	a := e.OnPeriod(period(2, cq("3Y0J", NeedSlot, -1), cq("VP6D", NeedDXCC, -22)))
	if a.Kind != DoReply || a.Decode.Call != "VP6D" {
		t.Fatalf("picked %+v, want the new entity of the two listed", a)
	}
	// Working one of them leaves the other callable — the list is a hunt, not a
	// single request.
	done := callsMe("VP6D", NeedDXCC, -22)
	done.Msg = me + " VP6D RR73"
	a = e.OnPeriod(period(4, done, cq("3Y0J", NeedSlot, -1)))
	if a.Kind != DoReply || a.Decode.Call != "3Y0J" {
		t.Errorf("after working VP6D: %+v, want the other station on the list", a)
	}
}

// ── Two decoders at once (the split view) ─────────────────────────────────

func onInst(inst string, p Period) Period {
	p.Instance = inst
	for i := range p.Decodes {
		p.Decodes[i].Instance = inst
	}
	return p
}

func TestTheOtherReceiverCannotBreakTheQSOInProgress(t *testing.T) {
	e := on()
	// Calling a new band on receiver A.
	if a := e.OnPeriod(onInst("A", period(0, cq("DL1XX", NeedBand, -10)))); a.Decode.Call != "DL1XX" {
		t.Fatalf("first call went to %+v", a)
	}
	// Receiver B now hears a new ENTITY — a better catch by every rule. It must
	// still not be called: one station at a time, and the QSO in hand is the
	// one already under way.
	if a := e.OnPeriod(onInst("B", period(1, cq("RARE", NeedDXCC, -1)))); a.Kind != DoNothing {
		t.Errorf("the other receiver started a second QSO: %+v", a)
	}
	// And B's periods count no misses against A's target: the station is not
	// absent from B, it was never on that band.
	e.OnPeriod(onInst("B", period(3, cq("RARE", NeedDXCC, -1))))
	e.OnPeriod(onInst("B", period(5, cq("RARE", NeedDXCC, -1))))
	e.OnPeriod(onInst("B", period(7, cq("RARE", NeedDXCC, -1))))
	if e.Status().Misses != 0 || e.Target() != "DL1XX" {
		t.Errorf("misses = %d, target = %q — the other receiver's periods were counted",
			e.Status().Misses, e.Target())
	}
	// B transmitting its own QSO is not us calling DL1XX either.
	for i := 0; i < 9; i++ {
		e.NoteTX(TXState{Transmitting: true, Instance: "B", Msg: "DL1XX " + me + " JN36"})
	}
	if e.Status().Attempts != 0 {
		t.Errorf("attempts = %d from the other receiver's transmissions, want 0", e.Status().Attempts)
	}
	// A's own transmissions do count.
	e.NoteTX(TXState{Transmitting: true, Instance: "A", Msg: "DL1XX " + me + " JN36"})
	if e.Status().Attempts != 1 {
		t.Errorf("attempts = %d after one call from the calling receiver, want 1", e.Status().Attempts)
	}
	// Once the QSO is over, the other receiver's station is free to be taken.
	done := callsMe("DL1XX", NeedBand, -10)
	done.Msg = me + " DL1XX RR73"
	e.OnPeriod(onInst("A", period(9, done)))
	if a := e.OnPeriod(onInst("B", period(11, cq("RARE", NeedDXCC, -1)))); a.Decode.Call != "RARE" {
		t.Errorf("after the QSO ended, the other receiver was still locked out: %+v", a)
	}
}