package ckconfig

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"strings"
	"testing"

	commandkit "gitea.maximumdirect.net/eric/CommandKit"
	configkit "gitea.maximumdirect.net/eric/ConfigKit"
	"go.yaml.in/yaml/v4"
)

func TestConfigDiffExecutesWithDefaultAndExplicitYAMLAndInheritedSelections(t *testing.T) {
	type settings struct {
		Greeting string `yaml:"greeting"`
	}
	var selections []Selection
	app := newConfigTestApp(t, AppCommand(func(_ context.Context, selection Selection) (*configkit.Result[settings], error) {
		selections = append(selections, selection)
		value := "Hello"
		if selection.Config.Set && selection.Config.Value == "after.yml" {
			value = "Goodbye"
		}
		return configkit.Load(configkit.Mapping("selected configuration", map[string]any{"greeting": value}), configkit.Options[settings]{})
	}))
	var output bytes.Buffer
	outcome := app.Execute(context.Background(), []string{"config", "diff", "--config", "before.yml", "--overlay", "base", "--against-config", "after.yml"}, commandkit.Streams{Out: &output, Err: io.Discard})
	if outcome.Kind != commandkit.OutcomeSuccess {
		t.Fatalf("default YAML comparison outcome = %#v", outcome)
	}
	if len(selections) != 2 || !selections[0].Config.Set || selections[0].Config.Value != "before.yml" || !selections[1].Config.Set || selections[1].Config.Value != "after.yml" || selections[1].Overlay != selections[0].Overlay {
		t.Fatalf("comparison selections = %#v", selections)
	}
	var document yaml.Node
	if err := yaml.Unmarshal(output.Bytes(), &document); err != nil {
		t.Fatalf("default report is not YAML: %q: %v", output.String(), err)
	}
	changes := reportField(document.Content[0], "changes")
	if value := reportField(changes, "greeting"); value == nil || value.Value != "Goodbye" {
		t.Fatalf("public comparison output = %#v", document.Content[0])
	}

	output.Reset()
	outcome = app.Execute(context.Background(), []string{"config", "diff", "--format", "yaml", "--config", "before.yml", "--against-config", "before.yml"}, commandkit.Streams{Out: &output, Err: io.Discard})
	if outcome.Kind != commandkit.OutcomeSuccess {
		t.Fatalf("explicit YAML comparison outcome = %#v", outcome)
	}
	var equal yaml.Node
	if err := yaml.Unmarshal(output.Bytes(), &equal); err != nil {
		t.Fatalf("explicit YAML report is not YAML: %q: %v", output.String(), err)
	}
	if len(reportField(equal.Content[0], "additions").Content) != 0 || len(reportField(equal.Content[0], "changes").Content) != 0 || len(reportField(equal.Content[0], "deletions").Content) != 0 {
		t.Fatalf("equal comparison did not return empty categories: %q", output.String())
	}

	loadsBeforeText := len(selections)
	output.Reset()
	outcome = app.Execute(context.Background(), []string{"config", "diff", "--format", "text"}, commandkit.Streams{Out: &output, Err: io.Discard})
	if outcome.Kind != commandkit.OutcomeUsage || len(selections) != loadsBeforeText || output.Len() != 0 {
		t.Fatalf("text format outcome/work/output = %#v / %d / %q", outcome, len(selections)-loadsBeforeText, output.String())
	}
}

func TestConfigDiffRunsComparisonOnlyScopeAndRejectsUnsupportedScopeBeforeWork(t *testing.T) {
	var inputCalls, stateCalls, acquireCalls, compareCalls int
	app := newConfigTestApp(t, Command(Suite[struct{}, struct{}]{
		NewInput: func() struct{} { inputCalls++; return struct{}{} },
		NewState: func() struct{} { stateCalls++; return struct{}{} },
		Scopes: []Scope[struct{}, struct{}]{
			{Name: "app", Operations: []Operation{Diff}, Compare: func(context.Context, ComparisonRequest[struct{}], struct{}) (commandkit.Acquired[[]configkit.Difference], error) {
				compareCalls++
				return commandkit.Acquired[[]configkit.Difference]{}, nil
			}},
			{Name: "plain", Operations: []Operation{Show}, Acquire: func(context.Context, Request, struct{}, struct{}) (commandkit.Acquired[View], error) {
				acquireCalls++
				return commandkit.Acquired[View]{}, nil
			}},
		},
	}))
	var output bytes.Buffer
	outcome := app.Execute(context.Background(), []string{"config", "scopes"}, commandkit.Streams{Out: &output, Err: io.Discard})
	if outcome.Kind != commandkit.OutcomeSuccess || !strings.Contains(output.String(), "app: diff") {
		t.Fatalf("comparison-only discovery = %#v, %q", outcome, output.String())
	}
	output.Reset()
	outcome = app.Execute(context.Background(), []string{"config", "diff", "--scope", "app"}, commandkit.Streams{Out: &output, Err: io.Discard})
	if outcome.Kind != commandkit.OutcomeSuccess || compareCalls != 1 {
		t.Fatalf("comparison-only execution = %#v calls=%d", outcome, compareCalls)
	}
	inputsBefore, statesBefore := inputCalls, stateCalls
	output.Reset()
	outcome = app.Execute(context.Background(), []string{"config", "diff", "--scope", "plain"}, commandkit.Streams{Out: &output, Err: io.Discard})
	if outcome.Kind != commandkit.OutcomeUsage || inputCalls != inputsBefore || stateCalls != statesBefore || acquireCalls != 0 || compareCalls != 1 || output.Len() != 0 {
		t.Fatalf("unsupported scope outcome/work/output = %#v / %d,%d,%d,%d / %q", outcome, inputCalls, stateCalls, acquireCalls, compareCalls, output.String())
	}
}

func TestConfigDiffProviderFailureRetainsDiagnosticsAndCause(t *testing.T) {
	wantErr := errors.New("provider unavailable")
	diagnostic := commandkit.Diagnostic{Severity: commandkit.SeverityError, Write: func(writer io.Writer) error {
		_, err := io.WriteString(writer, "provider warning\n")
		return err
	}}
	app := newConfigTestApp(t, Command(Suite[struct{}, struct{}]{Scopes: []Scope[struct{}, struct{}]{{
		Name: "app", Operations: []Operation{Diff},
		Compare: func(context.Context, ComparisonRequest[struct{}], struct{}) (commandkit.Acquired[[]configkit.Difference], error) {
			return commandkit.Acquired[[]configkit.Difference]{Diagnostics: []commandkit.Diagnostic{diagnostic}}, fmt.Errorf("comparison setup: %w", wantErr)
		},
	}}}))
	var output bytes.Buffer
	outcome := app.Execute(context.Background(), []string{"config", "diff"}, commandkit.Streams{Out: &output, Err: io.Discard})
	if outcome.Kind != commandkit.OutcomeOperational || !errors.Is(outcome.Cause, wantErr) || outcome.ReportIncomplete || outcome.DeliveryError != nil || output.Len() != 0 || len(outcome.Diagnostics) < 1 || outcome.Diagnostics[0].Severity != commandkit.SeverityError {
		t.Fatalf("provider failure outcome/output = %#v / %q", outcome, output.String())
	}
}

func TestConfigDiffReportPreparationFailureWritesNoReport(t *testing.T) {
	app := newConfigTestApp(t, Command(Suite[struct{}, struct{}]{Scopes: []Scope[struct{}, struct{}]{{
		Name: "app", Operations: []Operation{Diff},
		Compare: func(context.Context, ComparisonRequest[struct{}], struct{}) (commandkit.Acquired[[]configkit.Difference], error) {
			return commandkit.Acquired[[]configkit.Difference]{Value: []configkit.Difference{{
				Path: configkit.Keys("invalid"), Right: configkit.ValueSnapshot{Present: true, YAML: "bad: ["},
			}}}, nil
		},
	}}}))
	var output bytes.Buffer
	outcome := app.Execute(context.Background(), []string{"config", "diff"}, commandkit.Streams{Out: &output, Err: io.Discard})
	if outcome.Kind != commandkit.OutcomeOperational || outcome.ReportIncomplete || outcome.DeliveryError != nil || output.Len() != 0 {
		t.Fatalf("report preparation failure outcome/output = %#v / %q", outcome, output.String())
	}
}

func TestConfigDiffCancellationAfterAcquisitionRetainsDiagnosticsWithoutWriting(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	diagnostic := commandkit.Diagnostic{Severity: commandkit.SeverityWarning, Write: func(io.Writer) error { return nil }}
	app := newConfigTestApp(t, Command(Suite[struct{}, struct{}]{Scopes: []Scope[struct{}, struct{}]{{
		Name: "app", Operations: []Operation{Diff},
		Compare: func(context.Context, ComparisonRequest[struct{}], struct{}) (commandkit.Acquired[[]configkit.Difference], error) {
			cancel()
			return commandkit.Acquired[[]configkit.Difference]{Diagnostics: []commandkit.Diagnostic{diagnostic}}, nil
		},
	}}}))
	defer cancel()
	var output bytes.Buffer
	outcome := app.Execute(ctx, []string{"config", "diff"}, commandkit.Streams{Out: &output, Err: io.Discard})
	if outcome.Kind != commandkit.OutcomeOperational || !errors.Is(outcome.Cause, context.Canceled) || outcome.ReportIncomplete || output.Len() != 0 || len(outcome.Diagnostics) < 1 || outcome.Diagnostics[0].Severity != commandkit.SeverityWarning {
		t.Fatalf("cancelled comparison outcome/output = %#v / %q", outcome, output.String())
	}
}

func TestConfigDiffOutputErrorsCarryIncompleteDeliveryOutcome(t *testing.T) {
	app := newConfigTestApp(t, Command(Suite[struct{}, struct{}]{Scopes: []Scope[struct{}, struct{}]{{
		Name: "app", Operations: []Operation{Diff},
		Compare: func(context.Context, ComparisonRequest[struct{}], struct{}) (commandkit.Acquired[[]configkit.Difference], error) {
			return commandkit.Acquired[[]configkit.Difference]{}, nil
		},
	}}}))
	wantErr := errors.New("output failed")
	for _, test := range []struct {
		name   string
		writer io.Writer
		want   error
	}{
		{name: "writer error", writer: failingOutput{err: wantErr}, want: wantErr},
		{name: "short write", writer: shortWriter{}, want: io.ErrShortWrite},
	} {
		t.Run(test.name, func(t *testing.T) {
			outcome := app.Execute(context.Background(), []string{"config", "diff"}, commandkit.Streams{Out: test.writer, Err: io.Discard})
			if outcome.Kind != commandkit.OutcomeOperational || !errors.Is(outcome.DeliveryError, test.want) || !errors.Is(outcome.Cause, test.want) || !outcome.ReportIncomplete {
				t.Fatalf("delivery failure outcome = %#v", outcome)
			}
		})
	}
}

func TestConfigDiffRepeatedInvocationsPrepareFreshInputsAndState(t *testing.T) {
	type input struct {
		ID    int
		Label string
	}
	type state struct{ ID int }
	label := commandkit.ValueFlag(commandkit.FlagMeta{Name: "label"}, (*string)(nil), parseConfigString,
		func(target *input, value commandkit.Supplied[string]) { target.Label = value.Value })
	var inputID, stateID int
	var observed []struct {
		left, right input
		state       *state
	}
	app := newConfigTestApp(t, Command(Suite[input, *state]{
		NewInput:  func() input { inputID++; return input{ID: inputID} },
		NewState:  func() *state { stateID++; return &state{ID: stateID} },
		Selectors: []Selector[input]{{Binding: label, Scopes: []string{"app"}}},
		Scopes: []Scope[input, *state]{{Name: "app", Operations: []Operation{Diff}, Compare: func(_ context.Context, request ComparisonRequest[input], shared *state) (commandkit.Acquired[[]configkit.Difference], error) {
			observed = append(observed, struct {
				left, right input
				state       *state
			}{request.Left.Input, request.Right.Input, shared})
			left, err := configkit.Load[struct {
				Label string `yaml:"label"`
			}](configkit.Mapping("left", map[string]any{"label": request.Left.Input.Label}))
			if err != nil {
				return commandkit.Acquired[[]configkit.Difference]{}, err
			}
			right, err := configkit.Load[struct {
				Label string `yaml:"label"`
			}](configkit.Mapping("right", map[string]any{"label": request.Right.Input.Label + "-right"}))
			if err != nil {
				return commandkit.Acquired[[]configkit.Difference]{}, err
			}
			differences, err := configkit.Diff(left, right)
			return commandkit.Acquired[[]configkit.Difference]{Value: differences}, err
		}}},
	}))
	for range 2 {
		outcome := app.Execute(context.Background(), []string{"config", "diff", "--label", "current"}, commandkit.Streams{Out: io.Discard, Err: io.Discard})
		if outcome.Kind != commandkit.OutcomeSuccess {
			t.Fatalf("comparison invocation outcome = %#v", outcome)
		}
	}
	if len(observed) != 2 || observed[0].left.ID == observed[0].right.ID || observed[1].left.ID == observed[1].right.ID || observed[0].left.ID == observed[1].left.ID || observed[0].right.ID == observed[1].right.ID {
		t.Fatalf("input instances were reused: %#v", observed)
	}
	if observed[0].left.Label != "current" || observed[0].right.Label != "current" || observed[1].left.Label != "current" || observed[1].right.Label != "current" {
		t.Fatalf("comparison inputs missed captured flag values: %#v", observed)
	}
	if observed[0].state == nil || observed[1].state == nil || observed[0].state == observed[1].state || observed[0].state.ID != 1 || observed[1].state.ID != 2 {
		t.Fatalf("state was not fresh per invocation: %#v", observed)
	}
}

func TestConfigDiffExecutesConcealedChangesAndEmptyResults(t *testing.T) {
	type settings struct {
		Secret string `yaml:"secret"`
	}
	app := newConfigTestApp(t, AppCommand(func(_ context.Context, selection Selection) (*configkit.Result[settings], error) {
		value := "same"
		if selection.Config.Set && selection.Config.Value == "after" {
			value = "changed-secret"
		}
		return configkit.Load(configkit.Mapping("selected", map[string]any{"secret": value}), configkit.Options[settings]{Definition: configkit.Definition[settings]{Secret: func(path configkit.Path) bool { return path.String() == "/secret" }}})
	}))
	var output bytes.Buffer
	outcome := app.Execute(context.Background(), []string{"config", "diff", "--config", "before", "--against-config", "after"}, commandkit.Streams{Out: &output, Err: io.Discard})
	if outcome.Kind != commandkit.OutcomeSuccess || !strings.Contains(output.String(), "[REDACTED]") || strings.Contains(output.String(), "changed-secret") {
		t.Fatalf("concealed comparison outcome/report = %#v / %q", outcome, output.String())
	}
	output.Reset()
	outcome = app.Execute(context.Background(), []string{"config", "diff", "--config", "before", "--against-config", "before"}, commandkit.Streams{Out: &output, Err: io.Discard})
	if outcome.Kind != commandkit.OutcomeSuccess || !strings.Contains(output.String(), "additions:") || !strings.Contains(output.String(), "changes:") || !strings.Contains(output.String(), "deletions:") {
		t.Fatalf("empty comparison outcome/report = %#v / %q", outcome, output.String())
	}
}