package bonfire

import (
	"bytes"
	"context"
	"errors"
	"flag"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"testing"
)

var update = flag.Bool("update", false, "rewrite golden files")

// goldenVersion is the fixed version line of every golden.
var goldenVersion = Version{App: "v1.4.0", Framework: "v0.3.2"}

// plainEnv clears the environment variables that force or detect color, so
// goldens render the same on every machine: no escape codes unless --ansi.
func plainEnv(t *testing.T) {
	t.Helper()
	for _, k := range []string{"FORCE_COLOR", "CLICOLOR_FORCE", "CLICOLOR", "COLORTERM", "NO_COLOR"} {
		t.Setenv(k, "")
		_ = os.Unsetenv(k)
	}
	t.Setenv("TERM", "dumb")
}

// goldenTokenCommand is the admin:token:create command of the D-14
// preview: value, bare and repeatable flags with defaults, long help and
// two examples. The values are fake.
func goldenTokenCommand() Command {
	return Command{
		Name:        "admin:token:create",
		Description: "Create a personal API token for a backend admin",
		Long:        "Creates a token for the admin with the given login and prints it once.\nStore it in the client right away; it cannot be shown again.",
		Args:        []Arg{{Name: "login", Description: "The admin's login", Required: true}},
		Flags: []Flag{
			{Name: "scopes", Description: "Comma-separated scopes", Default: "*"},
			{Name: "expires", Description: "Days until expiry", Default: "90"},
			{Name: "json", Description: "Print the token as JSON", Bare: true},
			{Name: "tag", Shorthand: "t", Description: "A tag for the token", Repeatable: true},
		},
		Examples: []Example{
			{Command: "admin:token:create jane --scopes=journal.*", Description: "Token for the MCP server, journal only"},
			{Command: "admin:token:create jane --json", Description: "Script-friendly output"},
		},
		Run: func(context.Context, Input, Output) error { return nil },
	}
}

// goldenCommands is the command set of the list goldens (D-13 preview plus
// a hidden and a passthrough command).
func goldenCommands() []Command {
	ok := func(context.Context, Input, Output) error { return nil }
	return []Command{
		{Name: "migrate", Description: "Run the database migrations", Run: ok},
		{Name: "serve", Description: "Serve the application", Run: ok},
		{Name: "admin:create", Description: "Create a backend administrator", Run: ok},
		goldenTokenCommand(),
		{Name: "make:command", Description: "Create a new console command", Run: ok},
		{Name: "make:model", Description: "Create a new model and migration", Run: ok},
		{Name: "acme:secret", Description: "Rotate the internal signing secret", Hidden: true, Run: ok},
		goldenPassthroughCommand(),
	}
}

// goldenPassthroughCommand forwards everything after its name.
func goldenPassthroughCommand() Command {
	return Command{
		Name:        "tool:exec",
		Description: "Run the bundled tool with its own arguments",
		Long:        "Everything after the command name reaches the tool unchanged, global flags included.",
		Passthrough: true,
		Args:        []Arg{{Name: "args", Description: "The tool's arguments"}},
		Examples:    []Example{{Command: "tool:exec --version", Description: "The tool's own version"}},
		Run:         func(context.Context, Input, Output) error { return nil },
	}
}

// runGolden executes args on a fresh root over commands and returns stdout
// and stderr.
func runGolden(t *testing.T, commands []Command, args ...string) (string, string, int) {
	t.Helper()
	var out, errW bytes.Buffer
	root, err := NewRootIO("acme", commands, strings.NewReader(""), &out, &errW, WithVersion(goldenVersion))
	if err != nil {
		t.Fatal(err)
	}
	code := Execute(context.Background(), root, args)
	return out.String(), errW.String(), code
}

// assertGolden compares got with testdata/<name>.golden, rewriting the file
// first when -update is set.
func assertGolden(t *testing.T, name string, got []byte) {
	t.Helper()
	path := filepath.Join("testdata", name+".golden")
	if *update {
		if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(path, got, 0o644); err != nil {
			t.Fatal(err)
		}
	}
	want, err := os.ReadFile(path)
	if err != nil {
		t.Fatalf("%s: %v (run go test -run %s -update to create it)", name, err, t.Name())
	}
	if !bytes.Equal(got, want) {
		t.Errorf("%s differs from %s\n%s", name, path, firstDiff(want, got))
	}
}

// firstDiff prints the first differing line of want and got with a little
// context, in a unified-diff-like form.
func firstDiff(want, got []byte) string {
	wl := strings.Split(string(want), "\n")
	gl := strings.Split(string(got), "\n")
	for i := 0; i < max(len(wl), len(gl)); i++ {
		var w, g string
		if i < len(wl) {
			w = wl[i]
		}
		if i < len(gl) {
			g = gl[i]
		}
		if w == g {
			continue
		}
		var b strings.Builder
		for j := max(0, i-2); j < i; j++ {
			fmt.Fprintf(&b, "  %q\n", wl[j])
		}
		fmt.Fprintf(&b, "- %q\n+ %q\n", w, g)
		return b.String()
	}
	return "(same lines, different line endings)"
}

// TestListGolden: the bare binary prints the D-13 list.
func TestListGolden(t *testing.T) {
	plainEnv(t)
	out, errOut, code := runGolden(t, goldenCommands())
	if code != ExitOK || errOut != "" {
		t.Fatalf("exit %d, stderr %q", code, errOut)
	}
	assertGolden(t, "list", []byte(out))
	for _, args := range [][]string{{"list"}, {"--help"}, {"-h"}, {"help"}, {"-v"}, {"--no-ansi"}} {
		again, _, code := runGolden(t, goldenCommands(), args...)
		if code != ExitOK || again != out {
			t.Errorf("%v: exit %d, output differs from the bare list:\n%s", args, code, firstDiff([]byte(out), []byte(again)))
		}
	}
}

// TestListAllGolden: list --all adds the hidden command.
func TestListAllGolden(t *testing.T) {
	plainEnv(t)
	out, _, code := runGolden(t, goldenCommands(), "list", "--all")
	if code != ExitOK {
		t.Fatalf("exit %d", code)
	}
	assertGolden(t, "list_all", []byte(out))
}

// TestListJSONGolden: list --format=json prints the catalog.
func TestListJSONGolden(t *testing.T) {
	plainEnv(t)
	out, _, code := runGolden(t, goldenCommands(), "list", "--format=json")
	if code != ExitOK {
		t.Fatalf("exit %d", code)
	}
	assertGolden(t, "list.json", []byte(out))
}

// TestListStyledGolden: --ansi styles the list in the palette (ANSI256),
// so a palette change shows up in review.
func TestListStyledGolden(t *testing.T) {
	plainEnv(t)
	out, _, code := runGolden(t, goldenCommands(), "--ansi")
	if code != ExitOK {
		t.Fatalf("exit %d", code)
	}
	if !strings.Contains(out, "\x1b[") {
		t.Fatalf("--ansi list has no escape codes:\n%q", out)
	}
	assertGolden(t, "list_styled", []byte(out))
}

// TestHelpGolden: admin:token:create --help in the D-14 layout.
func TestHelpGolden(t *testing.T) {
	plainEnv(t)
	out, _, code := runGolden(t, goldenCommands(), "admin:token:create", "--help")
	if code != ExitOK {
		t.Fatalf("exit %d", code)
	}
	assertGolden(t, "help_token_create", []byte(out))
}

// TestHelpPassthroughGolden: the help of a passthrough command, reached
// through help <command> because --help after its name is forwarded.
func TestHelpPassthroughGolden(t *testing.T) {
	plainEnv(t)
	out, _, code := runGolden(t, goldenCommands(), "help", "tool:exec")
	if code != ExitOK {
		t.Fatalf("exit %d", code)
	}
	assertGolden(t, "help_passthrough", []byte(out))
}

// TestHelpEqualsHelpFlag: help <command>, <command> --help and <command>
// -h print the same bytes, with or without global flags.
func TestHelpEqualsHelpFlag(t *testing.T) {
	plainEnv(t)
	for _, name := range []string{"admin:token:create", "migrate", "list", "help"} {
		want, _, code := runGolden(t, goldenCommands(), "help", name)
		if code != ExitOK || !strings.Contains(want, "Usage:\n") {
			t.Fatalf("help %s: exit %d\n%s", name, code, want)
		}
		for _, args := range [][]string{{name, "--help"}, {name, "-h"}, {"-v", "help", name}, {"--no-ansi", name, "--help"}} {
			got, _, code := runGolden(t, goldenCommands(), args...)
			if code != ExitOK || got != want {
				t.Errorf("%v: exit %d, differs from help %s:\n%s", args, code, name, firstDiff([]byte(want), []byte(got)))
			}
		}
	}
}

// TestErrorGolden: the error block of D-18 for a hint with {bin}, an
// unknown command with a suggestion and the -v chain, on stderr.
func TestErrorGolden(t *testing.T) {
	plainEnv(t)
	hinted := Command{Name: "make:plugin", Description: "Create a plugin", Run: func(context.Context, Input, Output) error {
		return WithHint(errors.New("No application found in /home/jane/acme/plugins."),
			"summer make:command needs an application root (summer.yaml).",
			"cd ..; {bin} make:command acme.blog:publish")
	}}
	chained := Command{Name: "db:check", Description: "Check the database", Run: func(context.Context, Input, Output) error {
		return fmt.Errorf("db:check: %w", fmt.Errorf("connect to 127.0.0.1:5432: %w", errors.New("connection refused")))
	}}
	commands := append(goldenCommands(), hinted, chained)

	cases := []struct {
		golden string
		args   []string
		code   int
	}{
		{"error_hint", []string{"make:plugin"}, ExitFailure},
		{"error_unknown_command", []string{"migrat"}, ExitUsage},
		{"error_chain_verbose", []string{"-v", "db:check"}, ExitFailure},
	}
	for _, tc := range cases {
		t.Run(tc.golden, func(t *testing.T) {
			out, errOut, code := runGolden(t, commands, tc.args...)
			if code != tc.code {
				t.Fatalf("exit %d, want %d", code, tc.code)
			}
			if out != "" {
				t.Errorf("the error block reached stdout:\n%s", out)
			}
			assertGolden(t, tc.golden, []byte(errOut))
		})
	}
}