package lottery

import (
	"context"
	"encoding/json"
	"testing"
)

func mustParams(t *testing.T, v any) json.RawMessage {
	t.Helper()
	b, err := json.Marshal(v)
	if err != nil {
		t.Fatalf("marshal params: %v", err)
	}
	return b
}

func TestEvaluator_HasSubscription(t *testing.T) {
	ev := NewRuleEvaluator()
	tree := &EligibilityRule{
		Type:   RuleTypeHasSubscription,
		Params: mustParams(t, map[string]int64{"min_days_remaining": 7}),
	}

	// 没订阅
	ok, unmet, err := ev.Evaluate(context.Background(), tree, RuleContext{})
	if err != nil {
		t.Fatalf("eval err: %v", err)
	}
	if ok || len(unmet) != 1 || unmet[0].Rule != RuleTypeHasSubscription {
		t.Fatalf("expected fail on no sub, got ok=%v unmet=%+v", ok, unmet)
	}

	// 有订阅但剩余不足
	ok, unmet, err = ev.Evaluate(context.Background(), tree, RuleContext{
		HasActiveSubscription: true,
		SubscriptionExpiresIn: 3 * 86400,
	})
	if err != nil {
		t.Fatalf("eval err: %v", err)
	}
	if ok {
		t.Fatalf("expected fail on 3 days < 7 required, got pass")
	}
	if len(unmet) != 1 || unmet[0].Required != 7 || unmet[0].Current != 3 {
		t.Fatalf("unmet mismatch: %+v", unmet)
	}

	// 有订阅剩余足够
	ok, _, err = ev.Evaluate(context.Background(), tree, RuleContext{
		HasActiveSubscription: true,
		SubscriptionExpiresIn: 30 * 86400,
	})
	if err != nil || !ok {
		t.Fatalf("expected pass on 30 days, got ok=%v err=%v", ok, err)
	}
}

func TestEvaluator_InviteCount(t *testing.T) {
	ev := NewRuleEvaluator()
	tree := &EligibilityRule{
		Type:   RuleTypeInviteCount,
		Params: mustParams(t, map[string]int64{"min": 3}),
	}
	ok, unmet, err := ev.Evaluate(context.Background(), tree, RuleContext{InviteCount: 1})
	if err != nil || ok {
		t.Fatalf("expected fail, got ok=%v err=%v", ok, err)
	}
	if unmet[0].Current != 1 || unmet[0].Required != 3 {
		t.Fatalf("expected current=1 required=3, got %+v", unmet[0])
	}

	ok, _, _ = ev.Evaluate(context.Background(), tree, RuleContext{InviteCount: 3})
	if !ok {
		t.Fatalf("expected pass with InviteCount=3")
	}
}

func TestEvaluator_ANDShort(t *testing.T) {
	ev := NewRuleEvaluator()
	tree := &EligibilityRule{
		Op: OpAND,
		Children: []*EligibilityRule{
			{Type: RuleTypeHasSubscription},
			{Type: RuleTypeInviteCount, Params: mustParams(t, map[string]int64{"min": 5})},
		},
	}
	ok, unmet, _ := ev.Evaluate(context.Background(), tree, RuleContext{
		HasActiveSubscription: true,
		InviteCount:           1,
	})
	if ok {
		t.Fatalf("expected AND to fail")
	}
	// AND 需要收集全部未通过项（这里只有 1 条）
	if len(unmet) != 1 || unmet[0].Rule != RuleTypeInviteCount {
		t.Fatalf("expected 1 unmet (invite_count), got %+v", unmet)
	}
}

func TestEvaluator_ORPassIgnoresChildUnmet(t *testing.T) {
	ev := NewRuleEvaluator()
	tree := &EligibilityRule{
		Op: OpOR,
		Children: []*EligibilityRule{
			{Type: RuleTypeInviteCount, Params: mustParams(t, map[string]int64{"min": 100})},
			{Type: RuleTypeHasSubscription}, // 会通过
		},
	}
	ok, unmet, _ := ev.Evaluate(context.Background(), tree, RuleContext{
		HasActiveSubscription: true,
		InviteCount:           0,
	})
	if !ok {
		t.Fatalf("expected OR to pass because one child passes")
	}
	if len(unmet) != 0 {
		t.Fatalf("OR pass should hide child failures, got %+v", unmet)
	}
}

func TestEvaluator_ORFailBubblesAllChildren(t *testing.T) {
	ev := NewRuleEvaluator()
	tree := &EligibilityRule{
		Op: OpOR,
		Children: []*EligibilityRule{
			{Type: RuleTypeInviteCount, Params: mustParams(t, map[string]int64{"min": 5})},
			{Type: RuleTypeHasSubscription},
		},
	}
	ok, unmet, _ := ev.Evaluate(context.Background(), tree, RuleContext{
		InviteCount: 1,
	})
	if ok {
		t.Fatalf("expected OR to fail")
	}
	if len(unmet) != 2 {
		t.Fatalf("expected 2 unmet reasons on OR fail, got %+v", unmet)
	}
}

func TestEvaluator_SubscriptionType(t *testing.T) {
	ev := NewRuleEvaluator()
	tree := &EligibilityRule{
		Type:   RuleTypeSubscriptionType,
		Params: mustParams(t, map[string][]int64{"plan_ids": {10, 20}}),
	}
	ok, _, _ := ev.Evaluate(context.Background(), tree, RuleContext{
		SubscriptionPlanIds: []int64{20},
	})
	if !ok {
		t.Fatalf("expected pass when user plan matches")
	}
	ok, _, _ = ev.Evaluate(context.Background(), tree, RuleContext{
		SubscriptionPlanIds: []int64{99},
	})
	if ok {
		t.Fatalf("expected fail when user plan not in whitelist")
	}
}

func TestEvaluator_UserTag(t *testing.T) {
	ev := NewRuleEvaluator()
	tree := &EligibilityRule{
		Type:   RuleTypeUserTag,
		Params: mustParams(t, map[string][]string{"tags": {"vip", "beta"}}),
	}
	ok, _, _ := ev.Evaluate(context.Background(), tree, RuleContext{UserTags: []string{"beta"}})
	if !ok {
		t.Fatalf("expected pass when any tag matches")
	}
	ok, _, _ = ev.Evaluate(context.Background(), tree, RuleContext{UserTags: []string{"foo"}})
	if ok {
		t.Fatalf("expected fail when no tags match")
	}
}

func TestEvaluator_NilTreeAlwaysPasses(t *testing.T) {
	ev := NewRuleEvaluator()
	ok, unmet, err := ev.Evaluate(context.Background(), nil, RuleContext{})
	if err != nil || !ok || len(unmet) != 0 {
		t.Fatalf("nil tree should always pass; got ok=%v unmet=%+v err=%v", ok, unmet, err)
	}
}

func TestEvaluator_UnknownRuleType(t *testing.T) {
	ev := NewRuleEvaluator()
	tree := &EligibilityRule{Type: "no_such_rule"}
	_, _, err := ev.Evaluate(context.Background(), tree, RuleContext{})
	if err == nil {
		t.Fatalf("expected error on unknown rule type")
	}
}