package pathsafe

import (
	"errors"
	"path/filepath"
	"strings"
	"testing"
)

func TestNormalizeRelativeDestination(t *testing.T) {
	tests := []struct {
		name    string
		input   string
		want    string
		wantErr error
	}{
		{name: "simple", input: "artifacts/session_recap.md", want: "artifacts/session_recap.md"},
		{name: "backslashes become slashes", input: `artifacts\session_recap.md`, want: "artifacts/session_recap.md"},
		{name: "cleans dot segments", input: "artifacts/./session_recap.md", want: "artifacts/session_recap.md"},
		{name: "reject empty", input: "", wantErr: ErrRelativePathRequired},
		{name: "reject dot", input: ".", wantErr: ErrRelativePathRequired},
		{name: "reject unix absolute", input: "/artifacts/session_recap.md", wantErr: ErrRelativePathAbsolute},
		{name: "reject windows absolute", input: `C:\artifacts\session_recap.md`, wantErr: ErrRelativePathAbsolute},
		{name: "reject traversal", input: "../artifacts/session_recap.md", wantErr: ErrRelativePathEscape},
		{name: "reject traversal after clean", input: "a/../../session_recap.md", wantErr: ErrRelativePathEscape},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got, err := NormalizeRelativeDestination(tt.input)
			if tt.wantErr != nil {
				if !errors.Is(err, tt.wantErr) {
					t.Fatalf("NormalizeRelativeDestination() error = %v, want %v", err, tt.wantErr)
				}
				return
			}
			if err != nil {
				t.Fatalf("NormalizeRelativeDestination() error = %v", err)
			}
			if got != tt.want {
				t.Fatalf("NormalizeRelativeDestination() = %q, want %q", got, tt.want)
			}
		})
	}
}

func TestJoinSlashRelativeUnderRoot(t *testing.T) {
	root := filepath.Join(t.TempDir(), "session")

	tests := []struct {
		name    string
		input   string
		want    string
		wantErr error
	}{
		{name: "valid relative", input: "artifacts/session_recap.md", want: filepath.Join(root, "artifacts", "session_recap.md")},
		{name: "windows separators normalized", input: `artifacts\session_recap.md`, want: filepath.Join(root, "artifacts", "session_recap.md")},
		{name: "reject empty", input: "", wantErr: ErrRelativePathRequired},
		{name: "reject absolute", input: "/artifacts/session_recap.md", wantErr: ErrRelativePathAbsolute},
		{name: "reject traversal", input: "../artifacts/session_recap.md", wantErr: ErrRelativePathEscape},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got, err := JoinSlashRelativeUnderRoot(root, tt.input)
			if tt.wantErr != nil {
				if !errors.Is(err, tt.wantErr) {
					t.Fatalf("JoinSlashRelativeUnderRoot() error = %v, want %v", err, tt.wantErr)
				}
				return
			}
			if err != nil {
				t.Fatalf("JoinSlashRelativeUnderRoot() error = %v", err)
			}
			if got != tt.want {
				t.Fatalf("JoinSlashRelativeUnderRoot() = %q, want %q", got, tt.want)
			}
		})
	}
}

func TestSlashRelativeFromRoot(t *testing.T) {
	root := filepath.Join(t.TempDir(), "session")
	target := filepath.Join(root, "transcripts", "full.json")

	got, err := SlashRelativeFromRoot(root, target)
	if err != nil {
		t.Fatalf("SlashRelativeFromRoot() error = %v", err)
	}
	if got != "transcripts/full.json" {
		t.Fatalf("SlashRelativeFromRoot() = %q, want transcripts/full.json", got)
	}

	got, err = SlashRelativeFromRoot(root, `transcripts\full.json`)
	if err != nil {
		t.Fatalf("SlashRelativeFromRoot(relative with windows separators) error = %v", err)
	}
	if got != "transcripts/full.json" {
		t.Fatalf("SlashRelativeFromRoot(relative with windows separators) = %q, want transcripts/full.json", got)
	}
}

func TestSlashRelativeFromRootRejectsOutsideRoot(t *testing.T) {
	root := filepath.Join(t.TempDir(), "session")
	outside := filepath.Join(filepath.Dir(root), "outside", "file.txt")

	_, err := SlashRelativeFromRoot(root, outside)
	if !errors.Is(err, ErrRelativePathEscape) {
		t.Fatalf("SlashRelativeFromRoot() error = %v, want %v", err, ErrRelativePathEscape)
	}
}

func TestJoinSlashRelativeUnderRootRequiresRoot(t *testing.T) {
	_, err := JoinSlashRelativeUnderRoot("", "artifacts/session_recap.md")
	if err == nil || !strings.Contains(err.Error(), "root path is required") {
		t.Fatalf("JoinSlashRelativeUnderRoot() error = %v, want root-required error", err)
	}
}