package commandkit

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

func routeTestApp(t *testing.T, extra ...Declaration) *App {
	t.Helper()
	collections := simpleRunnable("collections")
	list := Group("list", "List", collections)
	testCommand := runnableWithOperands("test", 0, 1)
	promptkit := Group("promptkit", "PromptKit", list, testCommand)
	run := runnableWithOperands("run", 0, 1)
	inspect := runnableWithOperands("inspect", 1, 1)
	declarations := []Declaration{
		promptkit,
		run,
		inspect,
		Alias("collections", "list collections"),
		Alias("list collections", "promptkit list collections"),
		Alias("pk", "promptkit"),
		Alias("promptkit list bundles", "promptkit list collections"),
		Alias("smoke", "promptkit test"),
		Alias("r", "run"),
		Alias("r full", "inspect"),
	}
	declarations = append(declarations, extra...)
	app, err := New(Identity{Name: "Example"}, declarations...)
	if err != nil {
		t.Fatal(err)
	}
	return app
}

func TestEnteredRoutesResolveChainsAndPreserveTokenOrigins(t *testing.T) {
	app := routeTestApp(t)
	snapshot := app.routeSnapshot()
	for _, test := range []struct {
		name      string
		args      []string
		entered   string
		canonical string
		wantArgs  []string
		wantKind  routeKind
	}{
		{
			name:      "command alias chain",
			args:      []string{"collections", "--tag", "first"},
			entered:   "collections",
			canonical: "promptkit list collections",
			wantArgs:  []string{"promptkit", "list", "collections", "--tag", "first"},
			wantKind:  routeCanonical,
		},
		{
			name:      "group alias composition",
			args:      []string{"pk", "list", "bundles"},
			entered:   "pk list bundles",
			canonical: "promptkit list collections",
			wantArgs:  []string{"promptkit", "list", "collections"},
			wantKind:  routeCanonical,
		},
		{
			name:      "smoke operand",
			args:      []string{"smoke", "all"},
			entered:   "smoke",
			canonical: "promptkit test",
			wantArgs:  []string{"promptkit", "test", "all"},
			wantKind:  routeCanonical,
		},
		{
			name:      "explicit longer alternate spelling",
			args:      []string{"r", "full"},
			entered:   "r full",
			canonical: "inspect",
			wantArgs:  []string{"inspect"},
			wantKind:  routeCanonical,
		},
		{
			name:      "canonical runnable operand",
			args:      []string{"run", "full"},
			entered:   "run",
			canonical: "run",
			wantArgs:  []string{"run", "full"},
			wantKind:  routeCanonical,
		},
		{
			name:      "single dash remains an operand",
			args:      []string{"run", "-"},
			entered:   "run",
			canonical: "run",
			wantArgs:  []string{"run", "-"},
			wantKind:  routeCanonical,
		},
		{
			name:     "unknown path",
			args:     []string{"missing", "route"},
			entered:  "missing route",
			wantArgs: []string{"missing", "route"},
			wantKind: routeUnknown,
		},
		{
			name:     "space-containing token is not split",
			args:     []string{"collections list"},
			entered:  "collections list",
			wantArgs: []string{"collections list"},
			wantKind: routeUnknown,
		},
		{
			name:      "flag values and spaced tokens",
			args:      []string{"collections", "--message", "--hlep", "--text=two words"},
			entered:   "collections",
			canonical: "promptkit list collections",
			wantArgs:  []string{"promptkit", "list", "collections", "--message", "--hlep", "--text=two words"},
			wantKind:  routeCanonical,
		},
		{
			name:      "terminator stops command matching",
			args:      []string{"collections", "--", "r", "full"},
			entered:   "collections",
			canonical: "promptkit list collections",
			wantArgs:  []string{"promptkit", "list", "collections", "--", "r", "full"},
			wantKind:  routeCanonical,
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			got := resolveEnteredRoute(test.args, snapshot)
			if got.kind != test.wantKind {
				t.Fatalf("route kind = %d, want %d", got.kind, test.wantKind)
			}
			if got.enteredPath.String() != test.entered {
				t.Errorf("entered path = %q, want %q", got.enteredPath.String(), test.entered)
			}
			if got.canonicalPath.String() != test.canonical {
				t.Errorf("canonical path = %q, want %q", got.canonicalPath.String(), test.canonical)
			}
			if !reflect.DeepEqual(got.args, test.wantArgs) {
				t.Errorf("routed args = %q, want %q", got.args, test.wantArgs)
			}
		})
	}
}

func TestLongerRouteSelectionDoesNotFallBackAfterTargetParsingFails(t *testing.T) {
	app := routeTestApp(t)
	result := resolveEnteredRoute([]string{"r", "full"}, app.routeSnapshot())
	if got, want := result.canonicalPath.String(), "inspect"; got != want {
		t.Fatalf("canonical path = %q, want %q", got, want)
	}

	var diagnostics bytes.Buffer
	outcome := app.Execute(context.Background(), []string{"r", "full"}, Streams{Out: io.Discard, Err: &diagnostics})
	if outcome.Kind != OutcomeUsage {
		t.Fatalf("outcome kind = %v, want usage; diagnostics: %s", outcome.Kind, diagnostics.String())
	}
}

func TestEnteredAliasCanSelectExplicitLongerMapping(t *testing.T) {
	app := routeTestApp(t, Alias("pk list bundles", "inspect"))
	result := resolveEnteredRoute([]string{"pk", "list", "bundles"}, app.routeSnapshot())
	if got, want := result.canonicalPath.String(), "inspect"; got != want {
		t.Fatalf("canonical path = %q, want %q", got, want)
	}
	if got, want := result.enteredPath.String(), "pk list bundles"; got != want {
		t.Fatalf("entered path = %q, want %q", got, want)
	}
}

func TestExecuteDispatchesEnteredAliasToCanonicalRunner(t *testing.T) {
	runs := 0
	command := NewCommand(CommandSpec[struct{}]{
		Name: "canonical", Summary: "Canonical",
		Run: func(Invocation, struct{}) Outcome {
			runs++
			return Success()
		},
	})
	app, err := New(Identity{Name: "Example"}, command, Alias("shortcut", "canonical"))
	if err != nil {
		t.Fatal(err)
	}

	outcome := app.Execute(context.Background(), []string{"shortcut"}, Streams{Out: io.Discard, Err: io.Discard})
	if outcome.Kind != OutcomeSuccess || runs != 1 {
		t.Fatalf("alias execution = (%v, runs %d), want success and one canonical run", outcome.Kind, runs)
	}
}

func TestInvocationReportsEnteredAndCanonicalPathsPerCall(t *testing.T) {
	type input struct {
		label  Supplied[string]
		values Supplied[[]string]
	}
	type observed struct {
		entered   string
		canonical string
		label     string
		values    []string
	}
	var calls []observed
	command := NewCommand(CommandSpec[input]{
		Name: "run",
		Flags: []Flag[input]{ValueFlag(FlagMeta{Name: "label"}, (*string)(nil),
			func(value string) (string, error) { return value, nil },
			func(target *input, label Supplied[string]) { target.label = label },
		)},
		Arguments: []Argument[input]{RepeatArgument(ArgumentMeta{Name: "value"}, 0, -1,
			func(value string) (string, error) { return value, nil },
			func(target *input, values Supplied[[]string]) { target.values = values },
		)},
		Run: func(inv Invocation, value input) Outcome {
			calls = append(calls, observed{
				entered:   inv.EnteredPath(),
				canonical: inv.CanonicalPath(),
				label:     value.label.Value,
				values:    append([]string(nil), value.values.Value...),
			})
			return Success()
		},
	})
	shortcut := Alias("shortcut", "workspace run")
	app, err := New(Identity{Name: "Example"}, Group("workspace", "Workspace", command), shortcut)
	if err != nil {
		t.Fatal(err)
	}

	for _, args := range [][]string{{"workspace", "run", "--label=first", "first"}, {"shortcut", "--label=second", "second"}, {"workspace", "run"}} {
		if outcome := app.Execute(context.Background(), args, Streams{Out: io.Discard, Err: io.Discard}); outcome.Kind != OutcomeSuccess {
			t.Fatalf("Execute(%q) = %v, want success", args, outcome.Kind)
		}
	}
	if len(calls) != 3 {
		t.Fatalf("handler calls = %d, want 3", len(calls))
	}
	want := []observed{
		{entered: "workspace run", canonical: "workspace run", label: "first", values: []string{"first"}},
		{entered: "shortcut", canonical: "workspace run", label: "second", values: []string{"second"}},
		{entered: "workspace run", canonical: "workspace run"},
	}
	if !reflect.DeepEqual(calls, want) {
		t.Fatalf("handler invocations = %#v, want %#v", calls, want)
	}

	secondApp, err := New(Identity{Name: "Another"}, Group("workspace", "Workspace", command), shortcut)
	if err != nil {
		t.Fatal(err)
	}
	if outcome := secondApp.Execute(context.Background(), []string{"shortcut"}, Streams{Out: io.Discard, Err: io.Discard}); outcome.Kind != OutcomeSuccess {
		t.Fatalf("reused declaration execution = %v, want success", outcome.Kind)
	}
	if got := calls[3]; got.entered != "shortcut" || got.canonical != "workspace run" || len(got.values) != 0 {
		t.Fatalf("reused declaration invocation = %#v", got)
	}

	var zero Invocation
	if zero.EnteredPath() != "" || zero.CanonicalPath() != "" {
		t.Fatalf("zero Invocation paths = (%q, %q), want empty paths", zero.EnteredPath(), zero.CanonicalPath())
	}
}

func TestPrivateCommandCallbacksReceiveResolvedInvocationPaths(t *testing.T) {
	var calls []Invocation
	command := Command{record: &commandRecord{
		name: "inspect",
		payload: typedCommand[struct{}]{
			spec: CommandSpec[struct{}]{Name: "inspect"},
			privateRun: func(exec commandExecution, _ struct{}) Outcome {
				calls = append(calls, exec.invocation)
				return Success()
			},
		},
	}}
	app, err := New(Identity{Name: "Example"}, command, Alias("shortcut", "inspect"))
	if err != nil {
		t.Fatal(err)
	}
	for _, args := range [][]string{{"inspect"}, {"shortcut"}} {
		if outcome := app.Execute(context.Background(), args, Streams{Out: io.Discard, Err: io.Discard}); outcome.Kind != OutcomeSuccess {
			t.Fatalf("Execute(%q) = %v, want success", args, outcome.Kind)
		}
	}
	if len(calls) != 2 || calls[0].EnteredPath() != "inspect" || calls[0].CanonicalPath() != "inspect" || calls[1].EnteredPath() != "shortcut" || calls[1].CanonicalPath() != "inspect" {
		t.Fatalf("private callback invocations = %#v", calls)
	}
}

func TestExecuteAppliesCanonicalCommandFlagAliasesAfterRouting(t *testing.T) {
	type input struct{ color string }
	var got string
	command := NewCommand(CommandSpec[input]{
		Name: "inspect",
		Flags: []Flag[input]{ValueFlag(FlagMeta{Name: "color", Short: "c"}, (*string)(nil),
			func(value string) (string, error) { return value, nil },
			func(target *input, supplied Supplied[string]) { target.color = supplied.Value },
		)},
		Run: func(_ Invocation, value input) Outcome {
			got = value.color
			return Success()
		},
	})
	app, err := New(Identity{Name: "Example"}, command,
		Alias("shortcut", "inspect"),
		FlagAliasFor("inspect", "--colour", "-c"),
	)
	if err != nil {
		t.Fatal(err)
	}

	outcome := app.Execute(context.Background(), []string{"shortcut", "--colour=blue"}, Streams{Out: io.Discard, Err: io.Discard})
	if outcome.Kind != OutcomeSuccess || got != "blue" {
		t.Fatalf("alias flag execution = (%v, color %q), want success and blue", outcome.Kind, got)
	}
}

func TestAliasConversionErrorsRetainOccurrenceAndEnteredUsage(t *testing.T) {
	colorFailure := errors.New("invalid color")
	tagFailure := errors.New("invalid tag")
	type input struct {
		color Supplied[string]
		tags  Supplied[[]string]
	}
	command := NewCommand(CommandSpec[input]{
		Name: "inspect",
		Flags: []Flag[input]{
			ValueFlag(FlagMeta{Name: "color"}, (*string)(nil), func(value string) (string, error) {
				if value == "bad" {
					return "", colorFailure
				}
				return value, nil
			}, func(target *input, value Supplied[string]) { target.color = value }),
			RepeatFlag(FlagMeta{Name: "tag"}, nil, func(value string) (string, error) {
				if value == "bad" {
					return "", tagFailure
				}
				return value, nil
			}, func(target *input, value Supplied[[]string]) { target.tags = value }),
		},
		Run: func(Invocation, input) Outcome { return Success() },
	})
	app, err := New(Identity{Name: "Example"}, command,
		Alias("shortcut", "inspect"),
		FlagAliasFor("inspect", "--colour", "--color"),
		FlagAliasFor("inspect", "--labels", "--tag"),
	)
	if err != nil {
		t.Fatal(err)
	}

	for _, test := range []struct {
		name       string
		args       []string
		cause      error
		binding    string
		spelling   string
		occurrence int
	}{
		{
			name:       "invalid scalar before valid overwrite",
			args:       []string{"shortcut", "--colour=bad", "--color=good"},
			cause:      colorFailure,
			binding:    "color",
			spelling:   "--colour",
			occurrence: 1,
		},
		{
			name:       "invalid repeat occurrence after mixed spelling",
			args:       []string{"shortcut", "--labels=first", "--tag=bad"},
			cause:      tagFailure,
			binding:    "tag",
			spelling:   "--tag",
			occurrence: 2,
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			var diagnostics bytes.Buffer
			outcome := app.Execute(context.Background(), test.args, Streams{Out: io.Discard, Err: &diagnostics})
			if outcome.Kind != OutcomeUsage {
				t.Fatalf("outcome kind = %v, want usage", outcome.Kind)
			}
			if !errors.Is(outcome.Cause, test.cause) {
				t.Fatalf("outcome cause = %v, want wrapped %v", outcome.Cause, test.cause)
			}
			var conversionErr *flagConversionError
			if !errors.As(outcome.Cause, &conversionErr) {
				t.Fatalf("outcome cause %T does not expose flag conversion context", outcome.Cause)
			}
			if conversionErr.binding != test.binding || conversionErr.spelling != test.spelling || conversionErr.occurrence != test.occurrence {
				t.Fatalf("conversion error = %#v, want binding/spelling/occurrence for %s %d", conversionErr, test.spelling, test.occurrence)
			}
			for _, fragment := range []string{fmt.Sprintf("flag %s occurrence %d: %s", test.spelling, test.occurrence, test.cause), "Usage: Example shortcut", "Alias for: Example inspect"} {
				if !strings.Contains(diagnostics.String(), fragment) {
					t.Errorf("diagnostics %q do not contain %q", diagnostics.String(), fragment)
				}
			}
		})
	}
}

func TestAliasUsageSurvivesRegistrationDuringExecution(t *testing.T) {
	for _, test := range []struct {
		name     string
		register func(*App) error
		wantErr  bool
	}{
		{
			name: "successful registration",
			register: func(app *App) error {
				return app.Register(NewCommand(CommandSpec[struct{}]{Name: "late", Run: func(Invocation, struct{}) Outcome { return Success() }}))
			},
		},
		{
			name:     "failed registration",
			register: func(app *App) error { return app.Register(Alias("shortcut", "other")) },
			wantErr:  true,
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			var app *App
			var registrationErr error
			command := NewCommand(CommandSpec[struct{}]{
				Name: "inspect",
				Run: func(Invocation, struct{}) Outcome {
					registrationErr = test.register(app)
					return Usage(errors.New("operation rejected"))
				},
			})
			var err error
			app, err = New(Identity{Name: "Example"}, command, Alias("shortcut", "inspect"))
			if err != nil {
				t.Fatal(err)
			}
			var diagnostics bytes.Buffer
			outcome := app.Execute(context.Background(), []string{"shortcut"}, Streams{Out: io.Discard, Err: &diagnostics})
			if outcome.Kind != OutcomeUsage {
				t.Fatalf("outcome kind = %v, want usage", outcome.Kind)
			}
			if (registrationErr != nil) != test.wantErr {
				t.Fatalf("registration error = %v, want error %t", registrationErr, test.wantErr)
			}
			for _, fragment := range []string{"operation rejected", "Usage: Example shortcut", "Alias for: Example inspect"} {
				if !strings.Contains(diagnostics.String(), fragment) {
					t.Errorf("diagnostics %q do not contain %q", diagnostics.String(), fragment)
				}
			}
		})
	}
}

func TestUnresolvedRouteUsageHasNoCanonicalAliasAnnotation(t *testing.T) {
	app := routeTestApp(t)
	var diagnostics bytes.Buffer
	outcome := app.Execute(context.Background(), []string{"missing", "route"}, Streams{Out: io.Discard, Err: &diagnostics})
	if outcome.Kind != OutcomeUsage {
		t.Fatalf("outcome kind = %v, want usage", outcome.Kind)
	}
	if strings.Contains(diagnostics.String(), "Alias for:") {
		t.Fatalf("unresolved route diagnostics invented a canonical target: %q", diagnostics.String())
	}

	diagnostics.Reset()
	outcome = app.Execute(context.Background(), []string{"r", "full", "--unknown"}, Streams{Out: io.Discard, Err: &diagnostics})
	if outcome.Kind != OutcomeUsage {
		t.Fatalf("unknown flag outcome kind = %v, want usage", outcome.Kind)
	}
	for _, fragment := range []string{"unknown flag", "Usage: Example r full", "Alias for: Example inspect"} {
		if !strings.Contains(diagnostics.String(), fragment) {
			t.Errorf("unknown flag diagnostics %q do not contain %q", diagnostics.String(), fragment)
		}
	}
}

func TestExecuteAppliesGlobalHelpAliasAtApplicationRoot(t *testing.T) {
	app, err := New(Identity{Name: "Example"}, FlagAlias("--hlep", "--help"))
	if err != nil {
		t.Fatal(err)
	}
	var output bytes.Buffer
	outcome := app.Execute(context.Background(), []string{"--hlep"}, Streams{Out: &output, Err: io.Discard})
	if outcome.Kind != OutcomeSuccess || !strings.Contains(output.String(), "Usage:") {
		t.Fatalf("root help alias outcome = %v, output %q", outcome.Kind, output.String())
	}
}

func TestAliasOnlyPrefixProducesDiscoveryRoute(t *testing.T) {
	app, err := New(Identity{Name: "Example"},
		Group("promptkit", "PromptKit", Group("list", "List", simpleRunnable("collections"))),
		Alias("list collections", "promptkit list collections"),
	)
	if err != nil {
		t.Fatal(err)
	}

	result := resolveEnteredRoute([]string{"list", "--help"}, app.routeSnapshot())
	if result.kind != routeDiscovery {
		t.Fatalf("route kind = %d, want discovery", result.kind)
	}
	if got, want := result.discoveryPath.String(), "list"; got != want {
		t.Fatalf("discovery path = %q, want %q", got, want)
	}
	if got, want := result.enteredPath.String(), "list"; got != want {
		t.Fatalf("entered path = %q, want %q", got, want)
	}
	if !reflect.DeepEqual(result.args, []string{"--help"}) {
		t.Fatalf("discovery args = %q, want [--help]", result.args)
	}
}

func TestAliasHelpTargetsGroupsAndDiscoveryViews(t *testing.T) {
	var inputBuilds, promptRuns int
	showPrompt := NewCommand(CommandSpec[struct{}]{
		Name: "prompt",
		NewInput: func() struct{} {
			inputBuilds++
			return struct{}{}
		},
		Flags: []Flag[struct{}]{ValueFlag(FlagMeta{Name: "format"}, (*string)(nil),
			func(value string) (string, error) { return value, nil },
			func(*struct{}, Supplied[string]) {},
		)},
		Run: func(Invocation, struct{}) Outcome {
			promptRuns++
			return Success()
		},
	})
	commands := Group("promptkit", "PromptKit",
		Group("list", "List", simpleRunnable("collections")),
		Group("show", "Show", showPrompt),
	)
	app, err := New(Identity{Name: "example"}, commands,
		Alias("list collections", "promptkit list collections"),
		Alias("promptkit list bundles", "promptkit list collections"),
		Alias("pk", "promptkit"),
		Alias("pk list bundles", "promptkit show prompt"),
		FlagAlias("--hlep", "--help"),
		FlagAliasFor("promptkit show prompt", "--fmt", "--format"),
	)
	if err != nil {
		t.Fatal(err)
	}
	for _, test := range []struct {
		name string
		args []string
		want []string
		omit []string
	}{
		{
			name: "explicit command help resolves entered target",
			args: []string{"help", "list", "collections"},
			want: []string{"Usage:\n  example list collections", "Alias for: example promptkit list collections"},
		},
		{
			name: "aliased help flag uses entered command path",
			args: []string{"list", "collections", "--hlep"},
			want: []string{"Usage:\n  example list collections", "Alias for: example promptkit list collections", "--hlep → --help"},
		},
		{
			name: "canonical group shows direct aliases",
			args: []string{"help", "promptkit", "list"},
			want: []string{"Command Aliases:", "bundles → promptkit list collections"},
		},
		{
			name: "group shortcut shows more-specific override",
			args: []string{"pk", "--help"},
			want: []string{"Usage:\n  example pk [flags]", "Alias for: example promptkit", "list bundles → promptkit show prompt"},
			omit: []string{"list bundles → promptkit list collections"},
		},
		{
			name: "explicit discovery target",
			args: []string{"help", "list"},
			want: []string{"Usage:\n  example list [command]", "Available Aliases:", "collections → promptkit list collections", "--hlep → --help"},
			omit: []string{"--fmt"},
		},
		{
			name: "discovery help flag",
			args: []string{"list", "--hlep"},
			want: []string{"Usage:\n  example list [command]", "collections → promptkit list collections"},
		},
		{
			name: "scoped flag alias appears on canonical command help",
			args: []string{"promptkit", "show", "prompt", "--hlep"},
			want: []string{"--fmt → --format"},
		},
		{
			name: "group excludes descendant scoped flag aliases",
			args: []string{"promptkit", "--help"},
			want: []string{"Command Aliases:"},
			omit: []string{"--fmt → --format"},
		},
		{
			name: "root lists explicit command aliases separately",
			args: []string{"--help"},
			want: []string{"Available Commands:", "Command Aliases:", "list collections → promptkit list collections", "pk → promptkit"},
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			var output bytes.Buffer
			outcome := app.Execute(context.Background(), test.args, Streams{Out: &output, Err: io.Discard})
			if outcome.Kind != OutcomeSuccess {
				t.Fatalf("Execute(%q) = %#v; output %q", test.args, outcome, output.String())
			}
			for _, fragment := range test.want {
				if !strings.Contains(output.String(), fragment) {
					t.Errorf("help output %q does not contain %q", output.String(), fragment)
				}
			}
			for _, fragment := range test.omit {
				if strings.Contains(output.String(), fragment) {
					t.Errorf("help output %q unexpectedly contains %q", output.String(), fragment)
				}
			}
		})
	}

	var diagnostics bytes.Buffer
	outcome := app.Execute(context.Background(), []string{"list"}, Streams{Out: io.Discard, Err: &diagnostics})
	if outcome.Kind != OutcomeUsage || !strings.Contains(outcome.Cause.Error(), "--help") {
		t.Fatalf("bare discovery prefix = %#v, diagnostics %q; want usage pointing to list --help", outcome, diagnostics.String())
	}
	if inputBuilds != 0 || promptRuns != 0 {
		t.Fatalf("help built %d inputs and ran %d commands", inputBuilds, promptRuns)
	}
}