package api

// P5b task 03: a question on a long PDF is answered (by BM25 first) instead of refused, and the
// envelope says how the digest was built.

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

	"git.wntrmute.dev/kyle/sift/internal/digest"
	"git.wntrmute.dev/kyle/sift/internal/pdftest"
)

// fakeModel answers /embed with a fixed vector and /chat with a one-word SSE reply.
func fakeModel(t *testing.T) *httptest.Server {
	mux := http.NewServeMux()
	mux.HandleFunc("/embed", func(w http.ResponseWriter, r *http.Request) {
		var body struct {
			Input []string `json:"input"`
		}
		_ = json.NewDecoder(r.Body).Decode(&body)
		var data []map[string]any
		for i := range body.Input {
			data = append(data, map[string]any{"index": i, "embedding": []float64{1, float64(i % 7)}})
		}
		_ = json.NewEncoder(w).Encode(map[string]any{"data": data})
	})
	mux.HandleFunc("/chat", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "text/event-stream")
		_, _ = w.Write([]byte(`data: {"choices":[{"delta":{"content":"answer (p. 3)"}}]}` + "\n\ndata: [DONE]\n\n"))
	})
	srv := httptest.NewServer(mux)
	t.Cleanup(srv.Close)
	return srv
}

func TestPDFLongQuestionIsAnswered(t *testing.T) {
	r := newPDFRig(t)
	m := fakeModel(t)
	db := r.s.Digest.Cache
	r.s.Digest = &digest.Engine{ChatURL: m.URL + "/chat", EmbedURL: m.URL + "/embed", Cache: db, Gate: digest.NewGate(2, 8, 5*time.Second), Client: m.Client()}
	var pages []string
	for p := 1; p <= 260; p++ { // ~260 pages × 40 lines: well over EmbedSyncMax chunks
		pages = append(pages, pdftest.Lorem(p, 40))
	}
	o := newOrigin(t, "application/pdf", pdftest.Build(pdftest.Doc{Title: "Long", Pages: pages}))
	code, out, _ := r.fetch(t, r.fleet, map[string]any{"url": o.srv.URL, "question": "what is on page three?", "context": false})
	if code != 200 {
		t.Fatalf("long question: %d %v, want 200 (P5a refused this)", code, out)
	}
	dg, _ := out["digest"].(map[string]any)
	if dg == nil || dg["retrieval"] != "bm25" || dg["embedded"] != 0.0 {
		t.Errorf("digest meta = %v, want retrieval bm25 and embedded 0 on the first question", dg)
	}
	if c, _ := out["content"].(string); !strings.Contains(c, "answer") {
		t.Errorf("content %q", c)
	}
}

func TestPDFSmallQuestionReportsRetrieval(t *testing.T) {
	r := newPDFRig(t)
	m := fakeModel(t)
	db := r.s.Digest.Cache
	r.s.Digest = &digest.Engine{ChatURL: m.URL + "/chat", EmbedURL: m.URL + "/embed", Cache: db, Gate: digest.NewGate(2, 8, 5*time.Second), Client: m.Client()}
	o := newOrigin(t, "application/pdf", threePDF())
	code, out, _ := r.fetch(t, r.fleet, map[string]any{"url": o.srv.URL, "question": "what is on page two?", "context": false})
	dg, _ := out["digest"].(map[string]any)
	if code != 200 || dg == nil || dg["retrieval"] != "whole" {
		t.Errorf("small document: %d digest %v, want retrieval whole", code, dg)
	}
}