package tlog

import (
	"context"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"strings"
	"sync"
	"testing"
	"time"

	"basicstack.de/proofedmesh/services/admin-api/internal/attest"
)

type fakeTLogServer struct {
	mu    sync.Mutex
	byHash map[string]attest.LogReceipt
	nextIdx int64
}

func newFakeServer() *fakeTLogServer {
	return &fakeTLogServer{byHash: make(map[string]attest.LogReceipt)}
}

func (f *fakeTLogServer) handler(t *testing.T) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/api/v1/log/entries" {
			t.Errorf("unexpected path %s", r.URL.Path)
		}
		var req submitRequest
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}
		// Verify content_hash matches the envelope on the wire.
		recomputed, _ := attest.EnvelopeContentHash(req.Envelope)
		if recomputed != req.ContentHash {
			http.Error(w, `{"error":"content_hash mismatch"}`, http.StatusConflict)
			return
		}
		f.mu.Lock()
		defer f.mu.Unlock()
		if existing, ok := f.byHash[req.ContentHash]; ok {
			w.Header().Set("Content-Type", "application/json")
			w.WriteHeader(http.StatusOK) // idempotent repeat
			_ = json.NewEncoder(w).Encode(existing)
			return
		}
		f.nextIdx++
		receipt := attest.LogReceipt{
			LogIndex:    f.nextIdx,
			ContentHash: req.ContentHash,
			LoggedAt:    time.Now().UTC(),
			InclusionProof: attest.InclusionProof{
				TreeSize:          f.nextIdx + 1,
				TreeRootHash:      "sha256:" + strings.Repeat("a", 64),
				SignedTreeHeadRef: "sha256:" + strings.Repeat("b", 64),
				Hashes:            []string{"sha256:" + strings.Repeat("c", 64)},
			},
		}
		f.byHash[req.ContentHash] = receipt
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusCreated)
		_ = json.NewEncoder(w).Encode(receipt)
	})
}

func sampleEnvelope() attest.Envelope {
	return attest.Envelope{
		PayloadType: "application/vnd.in-toto+json",
		Payload:     "aGVsbG8", // "hello" (base64url)
		Signatures:  []attest.EnvelopeSignature{{KeyID: "k", Sig: "c2ln"}},
	}
}

func TestSubmit_HappyPathAndIdempotency(t *testing.T) {
	f := newFakeServer()
	srv := httptest.NewServer(f.handler(t))
	defer srv.Close()
	s := HTTPSubmitter{BaseURL: srv.URL, TokenSource: attest.StaticToken("t")}
	env := sampleEnvelope()
	ch, err := attest.EnvelopeContentHash(env)
	if err != nil {
		t.Fatalf("content_hash: %v", err)
	}
	r1, err := s.Submit(context.Background(), env, ch)
	if err != nil {
		t.Fatalf("first submit: %v", err)
	}
	if r1.LogIndex != 1 {
		t.Errorf("first log_index: %d", r1.LogIndex)
	}
	// Re-submit must return the SAME log_index.
	r2, err := s.Submit(context.Background(), env, ch)
	if err != nil {
		t.Fatalf("second submit: %v", err)
	}
	if r2.LogIndex != 1 {
		t.Errorf("idempotent repeat log_index changed: %d", r2.LogIndex)
	}
}

func TestSubmit_RejectsContentHashMismatch(t *testing.T) {
	f := newFakeServer()
	srv := httptest.NewServer(f.handler(t))
	defer srv.Close()
	s := HTTPSubmitter{BaseURL: srv.URL, TokenSource: attest.StaticToken("t")}
	env := sampleEnvelope()
	_, err := s.Submit(context.Background(), env, "sha256:"+strings.Repeat("f", 64))
	if err == nil {
		t.Fatal("expected server to reject content_hash mismatch")
	}
}

func TestSubmit_SurfacesServerErrors(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		http.Error(w, "trillian down", http.StatusServiceUnavailable)
	}))
	defer srv.Close()
	s := HTTPSubmitter{BaseURL: srv.URL, TokenSource: attest.StaticToken("t")}
	_, err := s.Submit(context.Background(), sampleEnvelope(), "sha256:"+strings.Repeat("a", 64))
	if err == nil {
		t.Fatal("expected error from 503")
	}
	if !strings.Contains(err.Error(), "status 503") {
		t.Errorf("expected status in error, got %v", err)
	}
}

func TestSubmit_RejectsEmptyBaseURL(t *testing.T) {
	s := HTTPSubmitter{}
	_, err := s.Submit(context.Background(), sampleEnvelope(), "sha256:"+strings.Repeat("a", 64))
	if err == nil {
		t.Fatal("expected error for empty BaseURL")
	}
}