package downloader

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

func TestTaskValidateAndDerivedPaths(t *testing.T) {
	task := validTaskForTest()
	if err := task.Validate(); err != nil {
		t.Fatalf("Validate() error = %v", err)
	}
	paths, err := DeriveTaskPaths(filepath.Join(t.TempDir(), "downloads"), task.RequestID)
	if err != nil {
		t.Fatalf("DeriveTaskPaths() error = %v", err)
	}
	for _, path := range []string{
		paths.Metadata,
		paths.Backup,
		paths.Part,
		paths.Completed,
	} {
		relative, err := filepath.Rel(paths.Root, path)
		if err != nil || relative == ".." {
			t.Fatalf("derived path escapes root: %s", path)
		}
	}
}

func TestTaskRejectsInvalidFields(t *testing.T) {
	tests := []struct {
		name   string
		mutate func(*Task)
	}{
		{name: "request id", mutate: func(task *Task) { task.RequestID = "../escape" }},
		{name: "app id", mutate: func(task *Task) { task.AppID = "Bad App" }},
		{name: "URL", mutate: func(task *Task) { task.URL = "http://example.invalid/app.zip" }},
		{name: "state", mutate: func(task *Task) { task.Status = "unknown" }},
		{name: "negative done", mutate: func(task *Task) { task.Done = -1 }},
		{name: "done exceeds total", mutate: func(task *Task) { task.Done = task.Total + 1 }},
		{name: "unknown total value", mutate: func(task *Task) {
			task.TotalKnown = false
			task.Total = 10
		}},
		{name: "weak etag", mutate: func(task *Task) {
			task.Validator = EntityValidator{ETag: `W/"weak"`}
		}},
		{name: "failed without code", mutate: func(task *Task) {
			task.Status = StatusFailed
			task.ErrorCode = ""
		}},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			task := validTaskForTest()
			test.mutate(&task)
			if err := task.Validate(); !errors.Is(err, ErrInvalidTask) {
				t.Fatalf("Validate() error = %v, want %v", err, ErrInvalidTask)
			}
		})
	}
}

func TestValidatorsMatchRejectsDifferentKinds(t *testing.T) {
	expected := EntityValidator{ETag: `"v1"`}
	if validatorsMatch(expected, EntityValidator{LastModified: "Wed, 16 Jul 2026 10:00:00 GMT"}) {
		t.Fatal("ETag unexpectedly matched Last-Modified")
	}
	if validatorsMatch(expected, EntityValidator{ETag: `"v2"`}) {
		t.Fatal("different ETags matched")
	}
	if !validatorsMatch(expected, EntityValidator{}) {
		t.Fatal("absent response validator should not contradict If-Range")
	}
}

func validTaskForTest() Task {
	return Task{
		SchemaVersion: TaskSchemaVersion,
		RequestID:     "request-001",
		AppID:         "json-parser",
		URL:           "https://download.invalid/json-parser.zip",
		Status:        StatusQueued,
		TotalKnown:    true,
		Total:         42,
		CreatedAt:     "2026-07-16T00:00:00Z",
	}
}