package reconcile_test

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"sync"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"

	"git.d-ma.be/mathias/tapir/internal/progress"
	"git.d-ma.be/mathias/tapir/internal/reconcile"
)

// What Reconcile reports while it works (ADR-035): the comparison, then the deciding
// phase with the real number of model decisions as its total.

type repRec struct {
	mu     sync.Mutex
	events []string
}

func (r *repRec) add(e string) {
	r.mu.Lock()
	defer r.mu.Unlock()
	r.events = append(r.events, e)
}

func (r *repRec) Begin(key string, total int)  { r.add(fmt.Sprintf("begin:%s:%d", key, total)) }
func (r *repRec) Advance(key string, done int) { r.add(fmt.Sprintf("advance:%s:%d", key, done)) }
func (r *repRec) Done(key string)              { r.add("done:" + key) }
func (r *repRec) Fail(key string, _ error)     { r.add("fail:" + key) }
func (r *repRec) Note(string, ...any)          {}
func (r *repRec) joined() string {
	r.mu.Lock()
	defer r.mu.Unlock()
	return strings.Join(r.events, ",")
}
func withRep(r *repRec) context.Context { return progress.With(context.Background(), r) }
func reconcileWith(t *testing.T, ctx context.Context, base, alt string, adj reconcile.Adjudicator) error {
	t.Helper()
	_, err := reconcile.Reconcile(ctx, tr(base), tr(alt), adj, opts)
	return err
}

// two compound/filler disputes the model is never asked about, then two it is.
const (
	progBase = "i crossborder delen ska vi ju betala totalt 1015 kronor till SEB idag"
	progAlt  = "i crossborderdelen ska vi betala totalt 1050 kronor till SCB idag"
)

func TestReconcileProgress_TheDecidingPhaseTotalIsTheModelDecisionsNotTheDisputes(t *testing.T) {
	rep := &repRec{}

	require.NoError(t, reconcileWith(t, withRep(rep), progBase, progAlt, always(reconcile.VerdictAlt)))

	assert.Equal(t,
		"begin:compare:0,done:compare,begin:decide:2,advance:decide:1,advance:decide:2,done:decide",
		rep.joined(),
		"4 disputes, 2 settled without the model: the bar counts the 2 the model decides, so it can reach its end")
}

func TestReconcileProgress_TextsThatAgreeStillClosePhasesSoNothingIsLeftRunning(t *testing.T) {
	rep := &repRec{}

	require.NoError(t, reconcileWith(t, withRep(rep), "samma text hela vägen", "samma text hela vägen", always(reconcile.VerdictAlt)))

	assert.Equal(t, "begin:compare:0,done:compare,begin:decide:0,done:decide", rep.joined())
}

func TestReconcileProgress_AModelErrorStillCountsAsADecisionTaken(t *testing.T) {
	rep := &repRec{}
	adj := &scripted{fn: func(i int, _ reconcile.Request) (reconcile.Verdict, error) {
		if i == 0 {
			return reconcile.VerdictBase, errors.New("one timeout")
		}
		return reconcile.VerdictAlt, nil
	}}

	require.NoError(t, reconcileWith(t, withRep(rep), progBase, progAlt, adj))

	assert.Contains(t, rep.joined(), "advance:decide:1,advance:decide:2", "a spot that errored was still handled; the bar must move past it")
}

func TestReconcileProgress_TheBreakerTrippingShowsTheDecidingPhaseFailedNotDone(t *testing.T) {
	rep := &repRec{}
	adj := &scripted{fn: func(int, reconcile.Request) (reconcile.Verdict, error) {
		return reconcile.VerdictBase, errors.New("model down")
	}}
	small := opts
	small.BreakAfter = 2

	_, err := reconcile.Reconcile(withRep(rep), tr(progBase), tr(progAlt), adj, small)

	require.NoError(t, err, "a model that is down degrades the result; it does not fail the job")
	assert.Contains(t, rep.joined(), "fail:decide")
	assert.NotContains(t, rep.joined(), "done:decide")
}

func TestReconcileProgress_AShutdownIsNeitherDoneNorFailed(t *testing.T) {
	rep := &repRec{}
	ctx, cancel := context.WithCancel(withRep(rep))
	adj := &scripted{fn: func(int, reconcile.Request) (reconcile.Verdict, error) {
		cancel()
		return reconcile.VerdictAlt, nil
	}}

	err := reconcileWith(t, ctx, progBase, progAlt, adj)

	require.ErrorIs(t, err, context.Canceled)
	assert.NotContains(t, rep.joined(), "fail:decide")
	assert.NotContains(t, rep.joined(), "done:decide")
}