package ckprompt

import (
	"context"
	"errors"
	"strings"
	"testing"
	"testing/fstest"

	commandkit "gitea.maximumdirect.net/eric/CommandKit"
	"gitea.maximumdirect.net/eric/CommandKit/integrations/ckconfig"
	configkit "gitea.maximumdirect.net/eric/ConfigKit"
	promptkit "gitea.maximumdirect.net/eric/promptkit"
)

type validationFailOnGenerate struct{ calls int }

func (client *validationFailOnGenerate) Generate(context.Context, promptkit.GenerateRequest) (*promptkit.GenerateResponse, error) {
	client.calls++
	return nil, errors.New("request validation must not generate")
}

type validationCancelArtifactReader struct{ cancel context.CancelFunc }

func (reader validationCancelArtifactReader) Read(context.Context, promptkit.ArtifactRef) (*promptkit.Artifact, error) {
	reader.cancel()
	return nil, context.Canceled
}

func validationTestEngine(t *testing.T, configuration string, options ...promptkit.Option) *promptkit.Engine {
	t.Helper()
	inputs, err := promptkit.FilesystemInputs("request validation fixture", fstest.MapFS{
		"config/prompt.yml": &fstest.MapFile{Data: []byte(configuration)},
	}, "config")
	if err != nil {
		t.Fatal(err)
	}
	engine, err := promptkit.NewEngine(promptkit.Config{Sources: promptkit.ConfigurationSources{
		Underlays: []configkit.Underlay{{Inputs: inputs}},
	}}, options...)
	if err != nil {
		t.Fatalf("construct PromptKit validation fixture: %v", err)
	}
	return engine
}

func TestWithRequestValidationPreservesSuiteAndValidatesSeedWithoutBuilder(t *testing.T) {
	type contextKey struct{}
	type input struct{ value string }
	type state struct{ value string }

	ctx := context.WithValue(context.Background(), contextKey{}, "invocation")
	engine := adapterEngine(t)
	selection := ckconfig.Selection{Config: commandkit.Supplied[string]{Value: "config.yml", Set: true}}
	inspect := func(context.Context, RequirementsRequest, input, state) (commandkit.Acquired[*promptkit.RequirementInspection], error) {
		return commandkit.Acquired[*promptkit.RequirementInspection]{}, nil
	}
	newInput := func() input { return input{value: "factory"} }
	suite := Suite[input, state]{InspectRequirements: inspect, NewInput: newInput}
	loaderCalls := 0
	suite = WithRequestValidation(suite, func(gotContext context.Context, gotSelection ckconfig.Selection, gotInput input, gotState state) (*promptkit.Engine, error) {
		loaderCalls++
		if gotContext != ctx || gotContext.Value(contextKey{}) != "invocation" || gotSelection != selection || gotInput.value != "input" || gotState.value != "state" {
			t.Errorf("loader args = (%v, %#v, %#v, %#v)", gotContext, gotSelection, gotInput, gotState)
		}
		return engine, nil
	}, nil)
	if suite.InspectRequirements == nil || suite.NewInput == nil || suite.ValidateRequest == nil {
		t.Fatalf("composed suite lost a member or omitted validation: %#v", suite)
	}

	acquired, err := suite.ValidateRequest(ctx, ValidationRequest{
		Selection: selection,
		Request:   promptkit.RunRequest{PromptID: "empty", ProfileID: "default"},
	}, input{value: "input"}, state{value: "state"})
	if err != nil {
		t.Fatalf("validate seed request: %v", err)
	}
	if acquired.Value != (struct{}{}) || len(acquired.Diagnostics) != 0 || loaderCalls != 1 {
		t.Fatalf("acquisition = %#v, loader calls = %d", acquired, loaderCalls)
	}
}

func TestWithRequestValidationBuilderFailurePrecedesLoading(t *testing.T) {
	type input struct{ value string }
	type state struct{ value string }
	buildErr := errors.New("cannot build request")
	loadCalls, buildCalls := 0, 0
	suite := WithRequestValidation(
		Suite[input, state]{},
		func(context.Context, ckconfig.Selection, input, state) (*promptkit.Engine, error) {
			loadCalls++
			return nil, errors.New("loader should not run")
		},
		func(ctx context.Context, request ValidationRequest, gotInput input, gotState state) (promptkit.RunRequest, error) {
			buildCalls++
			if ctx == nil || request.Request.PromptID != "seed" || gotInput.value != "input" || gotState.value != "state" {
				t.Errorf("builder args = (%v, %#v, %#v, %#v)", ctx, request, gotInput, gotState)
			}
			return promptkit.RunRequest{}, buildErr
		},
	)

	_, err := suite.ValidateRequest(context.Background(), ValidationRequest{Request: promptkit.RunRequest{PromptID: "seed"}}, input{value: "input"}, state{value: "state"})
	if !errors.Is(err, buildErr) || buildCalls != 1 || loadCalls != 0 {
		t.Fatalf("validation = (%v), builder calls = %d, loader calls = %d", err, buildCalls, loadCalls)
	}
}

func TestWithRequestValidationRetainsNilLoaderIssueIndependently(t *testing.T) {
	firstIssue := errors.New("existing adapter issue")
	backing := make([]error, 1, 3)
	backing[0] = firstIssue
	existingCallback := func(context.Context, ValidationRequest, struct{}, struct{}) (commandkit.Acquired[struct{}], error) {
		return commandkit.Acquired[struct{}]{}, nil
	}
	suite := Suite[struct{}, struct{}]{ValidateRequest: existingCallback, issues: backing[:1]}
	composed := WithRequestValidation(suite, nil, nil)
	if composed.ValidateRequest == nil || len(composed.issues) != 2 {
		t.Fatalf("nil loader composition = %#v", composed)
	}
	if _, err := composed.ValidateRequest(context.Background(), ValidationRequest{}, struct{}{}, struct{}{}); err != nil {
		t.Fatalf("nil loader replaced the existing validation callback: %v", err)
	}
	if !errors.Is(composed.issues[0], firstIssue) || composed.issues[1] == nil || backing[:cap(backing)][1] != nil {
		t.Fatalf("issues = %#v, original backing = %#v", composed.issues, backing[:cap(backing)])
	}

	composed.ValidateRequest = nil
	if err := newPromptTestApp(t).Register(Command(composed)); err == nil || !strings.Contains(err.Error(), "PromptKit engine loader is nil") {
		t.Fatalf("installation did not report retained issue after capabilities were cleared: %v", err)
	}
}

func TestWithRequestValidationDelegatesNativeOutcomesWithoutModelCalls(t *testing.T) {
	client := &validationFailOnGenerate{}
	engine := validationTestEngine(t, adapterPrompt, promptkit.WithLLMClient(client))
	selection := ckconfig.Selection{Config: commandkit.Supplied[string]{Value: "selected.yml", Set: true}}
	suite := WithRequestValidation(Suite[struct{}, struct{}]{}, func(_ context.Context, gotSelection ckconfig.Selection, _, _ struct{}) (*promptkit.Engine, error) {
		if gotSelection != selection {
			t.Errorf("loader selection = %#v, want %#v", gotSelection, selection)
		}
		return engine, nil
	}, nil)

	for _, test := range []struct {
		name    string
		request promptkit.RunRequest
		want    error
	}{
		{name: "success", request: promptkit.RunRequest{PromptID: "briefing", ProfileID: "default", Inputs: map[string]promptkit.ArtifactRef{"topic": promptkit.Inline("release planning")}}},
		{name: "missing required input", request: promptkit.RunRequest{PromptID: "briefing", ProfileID: "default"}, want: promptkit.ErrPromptRender},
		{name: "invalid profile selection", request: promptkit.RunRequest{PromptID: "briefing", ProfileID: "missing", Inputs: map[string]promptkit.ArtifactRef{"topic": promptkit.Inline("release planning")}}, want: promptkit.ErrProfileNotFound},
		{name: "unloadable artifact", request: promptkit.RunRequest{PromptID: "briefing", ProfileID: "default", Inputs: map[string]promptkit.ArtifactRef{"topic": promptkit.File("missing-topic.txt")}}, want: promptkit.ErrArtifactLoad},
	} {
		t.Run(test.name, func(t *testing.T) {
			nativeErr := engine.ValidateRequest(context.Background(), test.request)
			acquired, adapterErr := suite.ValidateRequest(context.Background(), ValidationRequest{Selection: selection, Request: test.request}, struct{}{}, struct{}{})
			if test.want == nil {
				if nativeErr != nil || adapterErr != nil {
					t.Fatalf("native error = %v, adapter error = %v", nativeErr, adapterErr)
				}
				if acquired.Value != (struct{}{}) {
					t.Fatalf("successful acquisition = %#v", acquired)
				}
				return
			}
			if !errors.Is(nativeErr, test.want) || !errors.Is(adapterErr, test.want) {
				t.Fatalf("native error = %v, adapter error = %v, want both to match %v", nativeErr, adapterErr, test.want)
			}
		})
	}
	if client.calls != 0 {
		t.Fatalf("request validation made %d model calls", client.calls)
	}
}

func TestWithRequestValidationBuilderOutputReachesNativeValidation(t *testing.T) {
	type contextKey struct{}
	type input struct{ campaign string }
	type state struct{ token string }

	client := &validationFailOnGenerate{}
	engine := validationTestEngine(t, adapterPrompt, promptkit.WithLLMClient(client))
	ctx := context.WithValue(context.Background(), contextKey{}, "validation invocation")
	selection := ckconfig.Selection{Overlay: commandkit.Supplied[string]{Value: "campaign.yml", Set: true}}
	seed := promptkit.RunRequest{PromptID: "briefing", ProfileID: "default", Vars: map[string]string{"topic": "seed topic"}}
	wantInput, wantState := input{campaign: "spring"}, state{token: "shared"}
	builderCalls, loaderCalls := 0, 0
	suite := WithRequestValidation(Suite[input, state]{}, func(gotContext context.Context, gotSelection ckconfig.Selection, gotInput input, gotState state) (*promptkit.Engine, error) {
		loaderCalls++
		if gotContext != ctx || gotContext.Value(contextKey{}) != "validation invocation" || gotSelection != selection || gotInput != wantInput || gotState != wantState {
			t.Errorf("loader args = (%v, %#v, %#v, %#v)", gotContext, gotSelection, gotInput, gotState)
		}
		return engine, nil
	}, func(gotContext context.Context, request ValidationRequest, gotInput input, gotState state) (promptkit.RunRequest, error) {
		builderCalls++
		if gotContext != ctx || gotContext.Value(contextKey{}) != "validation invocation" || request.Selection != selection || request.Request.PromptID != seed.PromptID || request.Request.Vars["topic"] != "seed topic" || gotInput != wantInput || gotState != wantState {
			t.Errorf("builder args = (%v, %#v, %#v, %#v)", gotContext, request, gotInput, gotState)
		}
		built := request.Request
		built.Inputs = map[string]promptkit.ArtifactRef{"topic": promptkit.Inline("required artifact from builder")}
		built.SessionID = "builder-session"
		return built, nil
	})

	acquired, err := suite.ValidateRequest(ctx, ValidationRequest{Selection: selection, Request: seed}, wantInput, wantState)
	if err != nil || acquired.Value != (struct{}{}) || builderCalls != 1 || loaderCalls != 1 {
		t.Fatalf("built request validation = (%#v, %v), builder calls = %d, loader calls = %d", acquired, err, builderCalls, loaderCalls)
	}
	if client.calls != 0 {
		t.Fatalf("request validation made %d model calls", client.calls)
	}
}

func TestWithRequestValidationRetainsNilEngineAndLoadDiagnostics(t *testing.T) {
	request := ValidationRequest{Request: promptkit.RunRequest{PromptID: "empty", ProfileID: "default"}}
	nilEngineSuite := WithRequestValidation(Suite[struct{}, struct{}]{}, func(context.Context, ckconfig.Selection, struct{}, struct{}) (*promptkit.Engine, error) {
		return nil, nil
	}, nil)
	acquired, err := nilEngineSuite.ValidateRequest(context.Background(), request, struct{}{}, struct{}{})
	if err == nil || !strings.Contains(err.Error(), "nil engine") || len(acquired.Diagnostics) != 0 {
		t.Fatalf("nil engine result = (%#v, %v)", acquired, err)
	}

	_, loadErr := configkit.Load[map[string]any](configkit.Bytes("invalid validation configuration", []byte("broken: [")))
	if loadErr == nil {
		t.Fatal("invalid configuration unexpectedly loaded")
	}
	loadFailure := WithRequestValidation(Suite[struct{}, struct{}]{}, func(context.Context, ckconfig.Selection, struct{}, struct{}) (*promptkit.Engine, error) {
		return nil, loadErr
	}, nil)
	acquired, err = loadFailure.ValidateRequest(context.Background(), request, struct{}{}, struct{}{})
	var retained *configkit.LoadError
	if !errors.Is(err, loadErr) || !errors.As(err, &retained) || retained != loadErr || len(acquired.Diagnostics) == 0 {
		t.Fatalf("load failure = (%#v, %v), want original ConfigKit error and diagnostics", acquired, err)
	}
}

func TestWithRequestValidationCancellationBoundaries(t *testing.T) {
	engine := adapterEngine(t)
	request := ValidationRequest{Request: promptkit.RunRequest{PromptID: "missing", ProfileID: "default"}}

	t.Run("before builder", func(t *testing.T) {
		ctx, cancel := context.WithCancel(context.Background())
		cancel()
		builderCalls, loaderCalls := 0, 0
		suite := WithRequestValidation(Suite[int, int]{}, func(context.Context, ckconfig.Selection, int, int) (*promptkit.Engine, error) {
			loaderCalls++
			return engine, nil
		}, func(context.Context, ValidationRequest, int, int) (promptkit.RunRequest, error) {
			builderCalls++
			return request.Request, nil
		})
		acquired, err := suite.ValidateRequest(ctx, request, 0, 0)
		if !errors.Is(err, context.Canceled) || builderCalls != 0 || loaderCalls != 0 || len(acquired.Diagnostics) != 0 {
			t.Fatalf("pre-build cancellation = (%#v, %v), builder calls=%d, loader calls=%d", acquired, err, builderCalls, loaderCalls)
		}
	})

	t.Run("after builder", func(t *testing.T) {
		ctx, cancel := context.WithCancel(context.Background())
		builderCalls, loaderCalls := 0, 0
		suite := WithRequestValidation(Suite[int, int]{}, func(context.Context, ckconfig.Selection, int, int) (*promptkit.Engine, error) {
			loaderCalls++
			return engine, nil
		}, func(context.Context, ValidationRequest, int, int) (promptkit.RunRequest, error) {
			builderCalls++
			cancel()
			return request.Request, nil
		})
		acquired, err := suite.ValidateRequest(ctx, request, 0, 0)
		if !errors.Is(err, context.Canceled) || builderCalls != 1 || loaderCalls != 0 || len(acquired.Diagnostics) != 0 {
			t.Fatalf("post-build cancellation = (%#v, %v), builder calls=%d, loader calls=%d", acquired, err, builderCalls, loaderCalls)
		}
	})

	t.Run("during load retains load failure", func(t *testing.T) {
		_, loadErr := configkit.Load[map[string]any](configkit.Bytes("cancelled validation configuration", []byte("broken: [")))
		if loadErr == nil {
			t.Fatal("invalid configuration unexpectedly loaded")
		}
		ctx, cancel := context.WithCancel(context.Background())
		loaderCalls := 0
		suite := WithRequestValidation(Suite[int, int]{}, func(context.Context, ckconfig.Selection, int, int) (*promptkit.Engine, error) {
			loaderCalls++
			cancel()
			return nil, loadErr
		}, nil)
		acquired, err := suite.ValidateRequest(ctx, request, 0, 0)
		var retained *configkit.LoadError
		if !errors.Is(err, loadErr) || !errors.As(err, &retained) || retained != loadErr || len(acquired.Diagnostics) == 0 || loaderCalls != 1 {
			t.Fatalf("cancelled load = (%#v, %v), loader calls=%d", acquired, err, loaderCalls)
		}
	})

	t.Run("after successful load skips native validation", func(t *testing.T) {
		ctx, cancel := context.WithCancel(context.Background())
		defer cancel()
		loaderCalls := 0
		suite := WithRequestValidation(Suite[int, int]{}, func(context.Context, ckconfig.Selection, int, int) (*promptkit.Engine, error) {
			loaderCalls++
			cancel()
			return engine, nil
		}, nil)
		acquired, err := suite.ValidateRequest(ctx, request, 0, 0)
		if !errors.Is(err, context.Canceled) || loaderCalls != 1 || len(acquired.Diagnostics) != 0 {
			t.Fatalf("post-load cancellation = (%#v, %v), loader calls=%d", acquired, err, loaderCalls)
		}
	})

	t.Run("native artifact cancellation retains PromptKit category", func(t *testing.T) {
		ctx, cancel := context.WithCancel(context.Background())
		defer cancel()
		client := &validationFailOnGenerate{}
		engine := validationTestEngine(t, adapterPrompt, promptkit.WithArtifactReader(validationCancelArtifactReader{cancel: cancel}), promptkit.WithLLMClient(client))
		suite := WithRequestValidation(Suite[int, int]{}, func(context.Context, ckconfig.Selection, int, int) (*promptkit.Engine, error) {
			return engine, nil
		}, nil)
		request := ValidationRequest{Request: promptkit.RunRequest{
			PromptID:  "briefing",
			ProfileID: "default",
			Inputs:    map[string]promptkit.ArtifactRef{"topic": promptkit.File("cancel-topic.txt")},
		}}
		acquired, err := suite.ValidateRequest(ctx, request, 0, 0)
		if !errors.Is(err, promptkit.ErrArtifactLoad) || len(acquired.Diagnostics) != 0 {
			t.Fatalf("native artifact cancellation = (%#v, %v), want PromptKit artifact-load category", acquired, err)
		}
		if client.calls != 0 {
			t.Fatalf("request validation made %d model calls", client.calls)
		}
	})
}