package cmd

import (
	"bytes"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"testing"
	"time"

	"github.com/spf13/cobra"
	"github.com/warrenronsiek/ctask/internal/workspace"
)

// completionTestEnv mirrors listTestEnv but is duplicated here so the
// completion tests are self-contained and can vary the fixtures.
func completionTestEnv(t *testing.T) string {
	t.Helper()
	root := t.TempDir()
	mk := func(category, dirName, status, taskType string) {
		dir := filepath.Join(root, category, dirName)
		os.MkdirAll(dir, 0755)
		now := time.Now().UTC().Truncate(time.Second)
		slug := dirName[11:]
		meta := &workspace.TaskMeta{
			ID: "t", Slug: slug, Title: slug,
			CreatedAt: now, UpdatedAt: now,
			Status: status, Category: category, Type: taskType,
			Mode: "local", Agent: workspace.AgentSpec{Type: "claude"},
		}
		if status == "archived" {
			meta.ArchivedAt = &now
		}
		workspace.WriteMeta(filepath.Join(dir, "task.yaml"), meta)
	}
	mk("general", "2026-04-05_alpha-active", "active", "task")
	mk("general", "2026-04-04_beta-archived", "archived", "task")
	mk("projects", "2026-04-03_gamma-active", "active", "project")
	mk("projects", "2026-04-02_delta-archived", "archived", "project")
	return root
}

// callCompletion invokes a ValidArgsFunction directly under a CTASK_ROOT
// override, returning the candidate list (sorted for stable comparisons)
// and the shell directive.
func callCompletion(t *testing.T, root string, fn func(*cobra.Command, []string, string) ([]string, cobra.ShellCompDirective)) ([]string, cobra.ShellCompDirective) {
	t.Helper()
	prev := os.Getenv("CTASK_ROOT")
	os.Setenv("CTASK_ROOT", root)
	defer func() {
		if prev == "" {
			os.Unsetenv("CTASK_ROOT")
		} else {
			os.Setenv("CTASK_ROOT", prev)
		}
	}()
	candidates, dir := fn(nil, nil, "")
	sort.Strings(candidates)
	return candidates, dir
}

func TestCompleteWorkspacesActiveOnly(t *testing.T) {
	root := completionTestEnv(t)
	got, _ := callCompletion(t, root, completeWorkspaces(completionActive))
	want := []string{
		"2026-04-03_gamma-active",
		"2026-04-05_alpha-active",
	}
	if !equalStringSlices(got, want) {
		t.Errorf("active filter:\nwant %v\ngot  %v", want, got)
	}
}

func TestCompleteWorkspacesArchivedOnly(t *testing.T) {
	root := completionTestEnv(t)
	got, _ := callCompletion(t, root, completeWorkspaces(completionArchived))
	want := []string{
		"2026-04-02_delta-archived",
		"2026-04-04_beta-archived",
	}
	if !equalStringSlices(got, want) {
		t.Errorf("archived filter:\nwant %v\ngot  %v", want, got)
	}
}

func TestCompleteWorkspacesAny(t *testing.T) {
	root := completionTestEnv(t)
	got, _ := callCompletion(t, root, completeWorkspaces(completionAny))
	want := []string{
		"2026-04-02_delta-archived",
		"2026-04-03_gamma-active",
		"2026-04-04_beta-archived",
		"2026-04-05_alpha-active",
	}
	if !equalStringSlices(got, want) {
		t.Errorf("any filter:\nwant %v\ngot  %v", want, got)
	}
}

func TestCompleteWorkspacesSecondArgReturnsNoCompletion(t *testing.T) {
	// Once the user has typed the first positional arg, completion of further
	// args must not enumerate workspaces.
	root := completionTestEnv(t)
	prev := os.Getenv("CTASK_ROOT")
	os.Setenv("CTASK_ROOT", root)
	defer func() {
		if prev == "" {
			os.Unsetenv("CTASK_ROOT")
		} else {
			os.Setenv("CTASK_ROOT", prev)
		}
	}()
	candidates, dir := completeWorkspaces(completionAny)(nil, []string{"already-typed"}, "")
	if len(candidates) != 0 {
		t.Errorf("expected no candidates after first positional arg, got: %v", candidates)
	}
	if dir != cobra.ShellCompDirectiveNoFileComp {
		t.Errorf("expected ShellCompDirectiveNoFileComp, got: %v", dir)
	}
}

// genCompletion calls the shell-specific generator that Cobra's auto-injected
// `ctask completion <shell>` subcommand uses internally. Bypasses rootCmd
// argument-routing state so the tests are independent.
func genCompletion(shell string) (string, error) {
	var buf bytes.Buffer
	var err error
	switch shell {
	case "bash":
		err = rootCmd.GenBashCompletionV2(&buf, true)
	case "zsh":
		err = rootCmd.GenZshCompletion(&buf)
	case "fish":
		err = rootCmd.GenFishCompletion(&buf, true)
	case "powershell":
		err = rootCmd.GenPowerShellCompletionWithDesc(&buf)
	}
	return buf.String(), err
}

func TestCompletionBashGenerates(t *testing.T) {
	out, err := genCompletion("bash")
	if err != nil {
		t.Fatalf("GenBashCompletionV2: %v", err)
	}
	if len(out) == 0 {
		t.Fatal("expected non-empty bash completion script")
	}
	if !strings.Contains(out, "ctask") {
		t.Errorf("bash completion script should mention 'ctask':\n%s", truncate(out, 200))
	}
}

func TestCompletionPowerShellGenerates(t *testing.T) {
	out, err := genCompletion("powershell")
	if err != nil {
		t.Fatalf("GenPowerShellCompletionWithDesc: %v", err)
	}
	if len(out) == 0 {
		t.Fatal("expected non-empty powershell completion script")
	}
	if !strings.Contains(out, "ctask") {
		t.Errorf("powershell completion script should mention 'ctask':\n%s", truncate(out, 200))
	}
}

func TestCompletionZshGenerates(t *testing.T) {
	out, err := genCompletion("zsh")
	if err != nil {
		t.Fatalf("GenZshCompletion: %v", err)
	}
	if len(out) == 0 {
		t.Fatal("expected non-empty zsh completion script")
	}
}

func TestCompletionFishGenerates(t *testing.T) {
	out, err := genCompletion("fish")
	if err != nil {
		t.Fatalf("GenFishCompletion: %v", err)
	}
	if len(out) == 0 {
		t.Fatal("expected non-empty fish completion script")
	}
}

// TestCompletionSubcommandViaExecute verifies that the user-facing path
// `ctask completion bash` actually runs end-to-end through Cobra. Cobra
// adds the `completion` subcommand lazily on first Execute(), so a Find()
// before any Execute() returns "unknown command" — exercising the real
// path is the right test.
func TestCompletionSubcommandViaExecute(t *testing.T) {
	var buf bytes.Buffer
	rootCmd.SetOut(&buf)
	rootCmd.SetErr(&buf)
	defer rootCmd.SetOut(os.Stdout)
	defer rootCmd.SetErr(os.Stderr)

	rootCmd.SetArgs([]string{"completion", "bash"})
	defer rootCmd.SetArgs(nil)
	if err := rootCmd.Execute(); err != nil {
		t.Fatalf("rootCmd.Execute(\"completion\", \"bash\"): %v", err)
	}
	if buf.Len() == 0 {
		t.Fatal("expected non-empty bash completion via Execute")
	}
	if !strings.Contains(buf.String(), "ctask") {
		t.Errorf("end-to-end bash completion should mention 'ctask'")
	}
}

func equalStringSlices(a, b []string) bool {
	if len(a) != len(b) {
		return false
	}
	for i := range a {
		if a[i] != b[i] {
			return false
		}
	}
	return true
}

func truncate(s string, n int) string {
	if len(s) <= n {
		return s
	}
	return s[:n]
}