package llm

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"testing"

	ck "gitea.maximumdirect.net/eric/ConfigKit"
	"gitea.maximumdirect.net/eric/audita/internal/core/config"
	"gitea.maximumdirect.net/eric/audita/internal/framework/responseschema"
	"gitea.maximumdirect.net/eric/audita/internal/framework/structuredoutput"
	"gitea.maximumdirect.net/eric/audita/internal/prompts"
	pk "gitea.maximumdirect.net/eric/promptkit"
)

type reply struct {
	status  int
	content string
}

func adapterFixture(t *testing.T, replies []reply, retries, repairs int, hook func(*http.Request)) (*Runtime, *int, string) {
	t.Helper()
	count := 0
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		count++
		if hook != nil {
			hook(r)
		}
		step := replies[len(replies)-1]
		if count <= len(replies) {
			step = replies[count-1]
		}
		if step.status == 0 {
			connection, _, hijackErr := w.(http.Hijacker).Hijack()
			if hijackErr != nil {
				t.Error(hijackErr)
				return
			}
			_ = connection.Close()
			return
		}
		if step.status != http.StatusOK {
			w.WriteHeader(step.status)
			_, _ = fmt.Fprint(w, `{"error":{"message":"provider error"}}`)
			return
		}
		if step.content == "MALFORMED_ENVELOPE" {
			_, _ = fmt.Fprint(w, `{"choices":[]}`)
			return
		}
		encoded, _ := json.Marshal(step.content)
		w.Header().Set("Content-Type", "application/json")
		_, _ = fmt.Fprintf(w, `{"model":"returned-model","choices":[{"message":{"content":%s}}],"usage":{"prompt_tokens":2,"completion_tokens":3,"total_tokens":5}}`, encoded)
	}))
	t.Cleanup(server.Close)
	t.Setenv("ADAPTER_KEY", "adapter-secret")
	base := fmt.Sprintf("version: 2\nbackends:\n  offline:\n    endpoint: %s/v1\n    credential: ADAPTER_KEY\nllm:\n  proposal_profile: base\n  transient_retries: %d\n  repair_attempts: %d\n", server.URL, retries, repairs)
	dir := profileLayout(t, base, "")
	main := filepath.Join(dir, "config.yml")
	profile := "id: base\nbackend: offline\nmodel: full-model\n"
	if err := os.WriteFile(filepath.Join(dir, "profiles", "base.yaml"), []byte(profile), 0600); err != nil {
		t.Fatal(err)
	}
	loaded, err := config.Load(ck.File(main), "")
	if err != nil {
		t.Fatal(err)
	}
	runtime, err := NewRuntime(context.Background(), loaded.Config, main, server.Client())
	if err != nil {
		t.Fatal(err)
	}
	return runtime, &count, dir
}

func adapterRequest(schema responseschema.Key) structuredoutput.Request {
	id := prompts.PromptIDModuleGlossaryProposal
	vars := map[string]string{"TranscriptDescriptionBlock": "", "GlossaryJSON": "[]", "SectionJSON": "[]"}
	if schema == responseschema.ValidatorDecisionSetKey {
		id = prompts.PromptIDValidatorEditorialReview
		vars = map[string]string{"TranscriptDescriptionBlock": "", "PayloadJSON": "[]"}
	}
	return structuredoutput.Request{PromptID: id, PromptVersion: prompts.VersionV1, Variables: vars, Schema: schema, Context: structuredoutput.DiagnosticContext{ModuleKey: "glossary"}}
}

func TestPreparedAdapterRepairsAndClassifies(t *testing.T) {
	for _, schema := range []responseschema.Key{responseschema.CorrectionSetKey, responseschema.ValidatorDecisionSetKey} {
		valid := `{"corrections":[]}`
		if schema == responseschema.ValidatorDecisionSetKey {
			valid = `{"validations":[]}`
		}
		for _, tc := range []struct {
			name                                                      string
			replies                                                   []reply
			retries, repairs, attempts, repairCalls, transientRetries int
			malformed                                                 bool
			cause                                                     error
		}{
			{"success", []reply{{200, valid}}, 0, 0, 1, 0, 0, false, nil},
			{"repair succeeds", []reply{{200, `{"wrong":true}`}, {200, valid}}, 0, 1, 2, 1, 0, false, nil},
			{"repair exhausted", []reply{{200, `{"wrong":true}`}, {200, `{"wrong":true}`}}, 0, 1, 2, 1, 0, true, nil},
			{"429 recovery", []reply{{429, ""}, {200, valid}}, 1, 0, 2, 0, 1, false, nil},
			{"5xx recovery", []reply{{503, ""}, {200, valid}}, 1, 0, 2, 0, 1, false, nil},
			{"zero retry", []reply{{503, ""}}, 0, 0, 1, 0, 0, false, pk.ErrLLMGenerate},
			{"positive retry exhausted", []reply{{503, ""}, {503, ""}}, 1, 0, 2, 0, 1, false, pk.ErrRetriesExhausted},
			{"transport failure", []reply{{0, ""}}, 0, 0, 1, 0, 0, false, pk.ErrTransport},
			{"malformed envelope", []reply{{200, "MALFORMED_ENVELOPE"}}, 0, 0, 1, 0, 0, false, pk.ErrMalformedResponse},
			{"retry and repair", []reply{{503, ""}, {200, `{"wrong":true}`}, {503, ""}, {200, valid}}, 1, 1, 4, 1, 2, false, nil},
		} {
			t.Run(string(schema)+"/"+tc.name, func(t *testing.T) {
				runtime, count, _ := adapterFixture(t, tc.replies, tc.retries, tc.repairs, nil)
				role := "proposal"
				if schema == responseschema.ValidatorDecisionSetKey {
					role = "validation"
				}
				var events []pk.ExecutionEvent
				var records []structuredoutput.CallRecord
				client, err := runtime.NewRoleClient(role, CallHooks{OnEvent: func(e pk.ExecutionEvent) { events = append(events, e) }, OnCall: func(r structuredoutput.CallRecord) { records = append(records, r) }})
				if err != nil {
					t.Fatal(err)
				}
				var out map[string]any
				response, err := client.CompleteStructured(context.Background(), adapterRequest(schema), &out)
				if *count != tc.attempts {
					t.Fatalf("HTTP attempts=%d, want %d", *count, tc.attempts)
				}
				if tc.malformed != structuredoutput.IsMalformedError(err) {
					t.Fatalf("malformed classification: %v", err)
				}
				if tc.cause != nil && !errors.Is(err, tc.cause) {
					t.Fatalf("cause %v missing from %v", tc.cause, err)
				}
				if tc.cause == nil && !tc.malformed && err != nil {
					t.Fatal(err)
				}
				if tc.name == "zero retry" && errors.Is(err, pk.ErrRetriesExhausted) {
					t.Fatal("zero retry reported exhaustion")
				}
				if response.Prepared == nil || response.Prompt.DefinitionHash == "" || response.Prompt.RenderedHash == "" || response.Prompt.ProfileID != "base" || response.Prompt.BackendID != "offline" {
					t.Fatalf("prepared metadata missing: %+v", response)
				}
				if len(records) != 2 || records[0].Finished.IsZero() == false || records[1].Finished.IsZero() || records[1].Context.Role != role {
					t.Fatalf("logical records: %+v", records)
				}
				if tc.malformed && records[1].FinalContent == "" {
					t.Fatal("invalid final content lost")
				}
				if len(events) == 0 || events[len(events)-1].Kind != pk.ExecutionFinished || int(events[len(events)-1].RepairCalls) != tc.repairCalls || int(events[len(events)-1].TransientRetries) != tc.transientRetries {
					t.Fatalf("execution counts: %+v", events)
				}
				if err == nil && (out == nil || string(response.Content) != valid || response.TotalTokens != 5*(tc.repairCalls+1) || response.Model != "full-model") {
					t.Fatalf("decoded response: %+v, %v", response, out)
				}
			})
		}
	}
}

func TestPreparedAdapterMetadataAndTargetGuard(t *testing.T) {
	requestSeen := false
	var posted struct {
		Messages []structuredoutput.Message `json:"messages"`
	}
	runtime, count, _ := adapterFixture(t, []reply{{200, `{"corrections":[]}`}}, 0, 0, func(r *http.Request) {
		requestSeen = true
		if r.Header.Get("Authorization") != "Bearer adapter-secret" {
			t.Error("backend credential not used")
		}
		if err := json.NewDecoder(r.Body).Decode(&posted); err != nil {
			t.Error(err)
		}
	})
	client, err := runtime.NewRoleClient("proposal", CallHooks{})
	if err != nil {
		t.Fatal(err)
	}
	req := adapterRequest(responseschema.CorrectionSetKey)
	req.Variables["HardeningPolicy"] = "attacker-controlled"
	var out map[string]any
	response, err := client.CompleteStructured(context.Background(), req, &out)
	if err != nil {
		t.Fatal(err)
	}
	if !requestSeen || *count != 1 || response.Prepared == nil || len(response.Prepared.Messages) == 0 {
		t.Fatal("prepared call missing")
	}
	if len(posted.Messages) != len(response.Prepared.Messages) {
		t.Fatal("prepared and dispatched message counts differ")
	}
	for i := range posted.Messages {
		if posted.Messages[i] != response.Prepared.Messages[i] {
			t.Fatal("prepared messages differ from dispatched request")
		}
	}
	found := false
	for _, msg := range response.Prepared.Messages {
		if strings.Contains(msg.Content, prompts.HardeningText()) {
			found = true
		}
		if strings.Contains(msg.Content, "attacker-controlled") {
			t.Fatal("reserved hardening variable was overridden")
		}
	}
	if !found {
		t.Fatal("hardening policy missing")
	}
}

func TestPreparedAdapterRejectsTargetDriftAndPreparationErrors(t *testing.T) {
	runtime, count, dir := adapterFixture(t, []reply{{200, `{"corrections":[]}`}}, 0, 0, nil)
	client, err := runtime.NewRoleClient("proposal", CallHooks{})
	if err != nil {
		t.Fatal(err)
	}
	req := adapterRequest(responseschema.CorrectionSetKey)
	req.PromptID = "missing.prompt"
	var out map[string]any
	if _, err := client.CompleteStructured(context.Background(), req, &out); err == nil || *count != 0 {
		t.Fatalf("preparation failure dispatched: %v, %d", err, *count)
	}
	// PrepareExecution reloads the profile, so a changed target must be blocked.
	if err := os.WriteFile(filepath.Join(dir, "profiles", "base.yaml"), []byte("id: base\nbackend: offline\nendpoint: http://127.0.0.1:1/v1\nmodel: full-model\n"), 0600); err != nil {
		t.Fatal(err)
	}
	req = adapterRequest(responseschema.CorrectionSetKey)
	_, err = client.CompleteStructured(context.Background(), req, &out)
	if err == nil || !strings.Contains(err.Error(), "target changed") || *count != 0 {
		t.Fatalf("target drift dispatched: %v, %d", err, *count)
	}
}

func TestPreparedAdapterCancellationStopsRetryWait(t *testing.T) {
	runtime, count, _ := adapterFixture(t, []reply{{503, ""}}, 2, 0, nil)
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	var once sync.Once
	client, err := runtime.NewRoleClient("proposal", CallHooks{OnEvent: func(e pk.ExecutionEvent) {
		if e.Kind == pk.ExecutionAttempt && e.Dispatched {
			once.Do(cancel)
		}
	}})
	if err != nil {
		t.Fatal(err)
	}
	var out map[string]any
	_, err = client.CompleteStructured(ctx, adapterRequest(responseschema.CorrectionSetKey), &out)
	if !errors.Is(err, context.Canceled) || *count != 1 {
		t.Fatalf("cancellation: %v, HTTP calls=%d", err, *count)
	}
}