package knowledge

import (
	"context"
	"os"
	"path/filepath"
	"strings"
	"testing"
)

func TestLoadPresentFile(t *testing.T) {
	dir := t.TempDir()
	p := filepath.Join(dir, "knowledge.md")
	if err := os.WriteFile(p, []byte("  I am a focus-tool author.\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	got, err := NewFileSource(p).Load(context.Background(), "")
	if err != nil {
		t.Fatalf("Load: %v", err)
	}
	if got.Text != "I am a focus-tool author." {
		t.Errorf("Text = %q (whitespace should be trimmed)", got.Text)
	}
	if got.Path != p {
		t.Errorf("Path = %q, want %q", got.Path, p)
	}
}

func TestLoadAbsentFileIsNotError(t *testing.T) {
	p := filepath.Join(t.TempDir(), "missing.md")
	got, err := NewFileSource(p).Load(context.Background(), "")
	if err != nil {
		t.Fatalf("absent file must not error: %v", err)
	}
	if got.Text != "" {
		t.Errorf("Text = %q, want empty for absent file", got.Text)
	}
	if got.Path != p {
		t.Errorf("Path = %q, want %q even when absent", got.Path, p)
	}
}

func TestLoadExplicitPathBeatsDefault(t *testing.T) {
	dir := t.TempDir()
	def := filepath.Join(dir, "default.md")
	other := filepath.Join(dir, "other.md")
	if err := os.WriteFile(def, []byte("default"), 0o644); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(other, []byte("explicit"), 0o644); err != nil {
		t.Fatal(err)
	}
	got, err := NewFileSource(def).Load(context.Background(), other)
	if err != nil {
		t.Fatalf("Load: %v", err)
	}
	if got.Text != "explicit" || got.Path != other {
		t.Fatalf("explicit path ignored: %+v", got)
	}
}

func TestLoadTruncatesOversize(t *testing.T) {
	p := filepath.Join(t.TempDir(), "big.md")
	if err := os.WriteFile(p, []byte(strings.Repeat("a", maxProfileBytes+500)), 0o644); err != nil {
		t.Fatal(err)
	}
	got, err := NewFileSource(p).Load(context.Background(), "")
	if err != nil {
		t.Fatalf("Load: %v", err)
	}
	if len(got.Text) > maxProfileBytes+len("\n…(truncated)") {
		t.Errorf("Text not truncated: %d bytes", len(got.Text))
	}
	if !strings.HasSuffix(got.Text, "(truncated)") {
		t.Errorf("missing truncation marker: %q", got.Text[len(got.Text)-20:])
	}
}

func TestLoadWhitespaceOnlyIsAbsent(t *testing.T) {
	p := filepath.Join(t.TempDir(), "blank.md")
	if err := os.WriteFile(p, []byte("   \n\t\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	got, err := NewFileSource(p).Load(context.Background(), "")
	if err != nil {
		t.Fatalf("Load: %v", err)
	}
	if got.Text != "" {
		t.Errorf("whitespace-only should be empty, got %q", got.Text)
	}
}

func TestLoadReadErrorIsError(t *testing.T) {
	dir := t.TempDir() // a directory is not readable as a file
	if _, err := NewFileSource(dir).Load(context.Background(), ""); err == nil {
		t.Fatal("reading a directory should error")
	}
}