package adapters

import (
	"context"
	"errors"
	"testing"

	oppintel "github.com/missionworkforce/missionmatch/internal/modules/opportunity_intelligence"
)

// stubSource yields a fixed set of records, then returns its err (used to inject a throttle).
type stubSource struct {
	name string
	recs []oppintel.OpportunityRecord
	err  error
}

func (s *stubSource) Name() string { return s.name }

func (s *stubSource) Fetch(_ context.Context, yield func(oppintel.OpportunityRecord) error) error {
	for _, r := range s.recs {
		if e := yield(r); e != nil {
			return e
		}
	}
	return s.err
}

func caRec(id string) oppintel.OpportunityRecord {
	return oppintel.OpportunityRecord{SourceRecordID: id, Kind: oppintel.KindContractAward}
}

func collect(t *testing.T, src oppintel.OpportunitySource) ([]string, error) {
	t.Helper()
	var got []string
	err := src.Fetch(context.Background(), func(r oppintel.OpportunityRecord) error {
		got = append(got, r.SourceRecordID)
		return nil
	})
	return got, err
}

func TestFallbackUsesPrimaryWhenHealthy(t *testing.T) {
	primary := &stubSource{name: "SAM Contract Awards", recs: []oppintel.OpportunityRecord{caRec("a")}}
	fb := &stubSource{name: "USASpending", recs: []oppintel.OpportunityRecord{caRec("b")}}
	got, err := collect(t, NewFallbackAwardsSource(primary, fb))
	if err != nil {
		t.Fatalf("err = %v", err)
	}
	if len(got) != 1 || got[0] != "a" {
		t.Fatalf("a healthy primary should be used alone, got %v", got)
	}
}

func TestFallbackSwitchesWhenPrimaryFailsBeforeYield(t *testing.T) {
	primary := &stubSource{name: "SAM Contract Awards", err: oppintel.ErrThrottled}
	fb := &stubSource{name: "USASpending", recs: []oppintel.OpportunityRecord{caRec("b")}}
	got, err := collect(t, NewFallbackAwardsSource(primary, fb))
	if err != nil {
		t.Fatalf("a clean fallback should succeed, got %v", err)
	}
	if len(got) != 1 || got[0] != "b" {
		t.Fatalf("expected the fallback record, got %v", got)
	}
}

func TestFallbackDoesNotSwitchMidPull(t *testing.T) {
	primary := &stubSource{name: "SAM Contract Awards", recs: []oppintel.OpportunityRecord{caRec("a")}, err: oppintel.ErrThrottled}
	fb := &stubSource{name: "USASpending", recs: []oppintel.OpportunityRecord{caRec("b")}}
	got, err := collect(t, NewFallbackAwardsSource(primary, fb))
	if !errors.Is(err, oppintel.ErrThrottled) {
		t.Fatalf("a throttle after the primary yielded should surface, got %v", err)
	}
	if len(got) != 1 || got[0] != "a" {
		t.Fatalf("once the primary yields, the run must not switch feeds, got %v", got)
	}
}

func TestFallbackName(t *testing.T) {
	src := NewFallbackAwardsSource(&stubSource{name: "SAM Contract Awards"}, &stubSource{name: "USASpending"})
	if src.Name() != "SAM Contract Awards" {
		t.Fatalf("name should report the primary, got %q", src.Name())
	}
}