package sharedassets

import (
	"io/fs"
	"strings"
	"testing"
	"testing/fstest"
)

func TestModulePromptFSCombinesModuleAndSharedPrompts(t *testing.T) {
	fsys, err := ModulePromptFS("dnd.test", fstest.MapFS{
		"assets/prompts/dnd.test.yaml": {Data: []byte("id: dnd.test")},
		"assets/prompts/task.md":       {Data: []byte("task")},
	}, []ModulePromptFile{
		{Name: "dnd.test.yaml", Path: "assets/prompts/dnd.test.yaml"},
		{Name: "task.md", Path: "assets/prompts/task.md"},
	})
	if err != nil {
		t.Fatalf("ModulePromptFS() error = %v, want nil", err)
	}

	tests := map[string]string{
		"assets/prompts/dnd.test/dnd.test.yaml":                         "id: dnd.test",
		"assets/prompts/dnd.test/task.md":                               "task",
		"assets/prompts/dnd.test/sharedassets/common-dnd-system.md":     "",
		"assets/prompts/dnd.test/sharedassets/common-dnd-transcript.md": "",
		"assets/prompts/dnd.test/sharedassets/common-dnd-references.md": "",
	}
	for path, want := range tests {
		data, err := fs.ReadFile(fsys, path)
		if err != nil {
			t.Fatalf("ReadFile(%q) error = %v, want nil", path, err)
		}
		if len(data) == 0 {
			t.Fatalf("ReadFile(%q) returned empty content", path)
		}
		if want != "" && !strings.Contains(string(data), want) {
			t.Fatalf("ReadFile(%q) = %q, want substring %q", path, data, want)
		}
	}

	entries, err := fs.ReadDir(fsys, ".")
	if err != nil {
		t.Fatalf("ReadDir(.) error = %v, want nil", err)
	}
	if len(entries) != 1 || entries[0].Name() != "assets" || !entries[0].IsDir() {
		t.Fatalf("ReadDir(.) = %#v, want assets directory", entries)
	}
}

func TestModulePromptFSRejectsMissingModuleFile(t *testing.T) {
	_, err := ModulePromptFS("dnd.test", fstest.MapFS{}, []ModulePromptFile{
		{Name: "task.md", Path: "assets/prompts/task.md"},
	})
	if err == nil || !strings.Contains(err.Error(), "read module prompt asset assets/prompts/task.md") {
		t.Fatalf("ModulePromptFS() error = %v, want missing module asset context", err)
	}
}

func TestModulePromptFSRejectsMissingSharedFile(t *testing.T) {
	_, err := modulePromptFS("dnd.test", fstest.MapFS{
		"assets/prompts/task.md": {Data: []byte("task")},
	}, []ModulePromptFile{
		{Name: "task.md", Path: "assets/prompts/task.md"},
	}, fstest.MapFS{})
	if err == nil || !strings.Contains(err.Error(), "read shared prompt asset common-dnd-system.md") {
		t.Fatalf("modulePromptFS() error = %v, want missing shared asset context", err)
	}
}

func TestModulePromptFSRejectsNestedVirtualFileName(t *testing.T) {
	_, err := ModulePromptFS("dnd.test", fstest.MapFS{
		"assets/prompts/task.md": {Data: []byte("task")},
	}, []ModulePromptFile{
		{Name: "nested/task.md", Path: "assets/prompts/task.md"},
	})
	if err == nil || !strings.Contains(err.Error(), "must not contain path separators") {
		t.Fatalf("ModulePromptFS() error = %v, want nested file name error", err)
	}
}