package backendrpc

import (
	"bufio"
	"context"
	"encoding/json"
	"errors"
	"net"
	"testing"
	"time"
)

type testRequest struct {
	JSONRPC string          `json:"jsonrpc"`
	ID      json.RawMessage `json:"id"`
	Method  string          `json:"method"`
	Params  json.RawMessage `json:"params,omitempty"`
}

type testEnvelope struct {
	OK        bool   `json:"ok"`
	Status    string `json:"status"`
	Data      any    `json:"data,omitempty"`
	Error     any    `json:"error,omitempty"`
	RequestID string `json:"request_id"`
}

type testResponse struct {
	JSONRPC string          `json:"jsonrpc"`
	ID      json.RawMessage `json:"id"`
	Result  any             `json:"result,omitempty"`
	Error   *JSONRPCError   `json:"error,omitempty"`
}

func newTestClient(t *testing.T, handler func(t *testing.T, req testRequest) testResponse) *Client {
	t.Helper()
	client := New("bat.sock")
	client.DialContext = func(ctx context.Context, network string, address string) (net.Conn, error) {
		clientConn, serverConn := net.Pipe()
		go func(conn net.Conn) {
			defer conn.Close()
			line, err := bufio.NewReader(conn).ReadBytes('\n')
			if err != nil {
				return
			}
			var req testRequest
			if err := json.Unmarshal(line, &req); err != nil {
				return
			}
			resp := handler(t, req)
			if len(resp.ID) == 0 {
				resp.ID = req.ID
			}
			if resp.JSONRPC == "" {
				resp.JSONRPC = jsonRPCVersion
			}
			_ = json.NewEncoder(conn).Encode(resp)
		}(serverConn)
		return clientConn, nil
	}
	return client
}

func TestResourceRepairQueuesTask(t *testing.T) {
	client := newTestClient(t, func(t *testing.T, req testRequest) testResponse {
		if req.Method != "resource.repair" {
			t.Fatalf("method = %s", req.Method)
		}
		return testResponse{
			Result: testEnvelope{
				OK:        true,
				Status:    "accepted",
				RequestID: "req-test-1",
				Data: map[string]any{
					"task_id": "task-1",
					"kind":    "resource.repair",
				},
			},
		}
	})

	task, err := client.ResourceRepair(context.Background())
	if err != nil {
		t.Fatalf("ResourceRepair error: %v", err)
	}
	if task.TaskID != "task-1" || task.Kind != "resource.repair" {
		t.Fatalf("unexpected task: %#v", task)
	}
}

func TestResourceListSendsPagination(t *testing.T) {
	client := newTestClient(t, func(t *testing.T, req testRequest) testResponse {
		if req.Method != "resource.list" {
			t.Fatalf("method = %s", req.Method)
		}
		var params pageParam
		if err := json.Unmarshal(req.Params, &params); err != nil {
			t.Fatalf("decode params: %v", err)
		}
		if params.Offset != 2 || params.Limit != 1 {
			t.Fatalf("params = %#v", params)
		}
		bytes := uint64(42)
		return testResponse{
			Result: testEnvelope{
				OK:        true,
				Status:    "ok",
				RequestID: "req-test-2",
				Data: map[string]any{
					"available":        true,
					"resource_root":    "/tmp/resources/current",
					"manifest_version": 1,
					"total_entries":    3,
					"offset":           2,
					"limit":            1,
					"entries": []map[string]any{
						{
							"url":         "https://example.invalid/a.zip",
							"destination": "a.zip",
							"bytes":       bytes,
							"blake3":      "abc",
						},
					},
				},
			},
		}
	})

	page, err := client.ResourceList(context.Background(), 2, 1)
	if err != nil {
		t.Fatalf("ResourceList error: %v", err)
	}
	if !page.Available || page.TotalEntries != 3 || len(page.Entries) != 1 {
		t.Fatalf("unexpected page: %#v", page)
	}
	if page.Entries[0].Bytes == nil || *page.Entries[0].Bytes != 42 {
		t.Fatalf("unexpected entry bytes: %#v", page.Entries[0].Bytes)
	}
}

func TestApplicationErrorReturnsAPIError(t *testing.T) {
	client := newTestClient(t, func(t *testing.T, req testRequest) testResponse {
		if req.Method != "task.status" {
			t.Fatalf("method = %s", req.Method)
		}
		return testResponse{
			Result: testEnvelope{
				OK:     false,
				Status: "error",
				Error: APIError{
					Code:      "BAT-ERR-700004",
					Kind:      "task_not_found",
					Domain:    "rpc",
					Location:  "task.status",
					Message:   "任务不存在：missing",
					Retryable: false,
				},
				RequestID: "req-test-3",
			},
		}
	})

	_, err := client.TaskStatus(context.Background(), "missing")
	var apiErr *APIError
	if !errors.As(err, &apiErr) {
		t.Fatalf("expected APIError, got %T %v", err, err)
	}
	if apiErr.Code != "BAT-ERR-700004" {
		t.Fatalf("code = %s", apiErr.Code)
	}
}

func TestTransportErrorReturnsJSONRPCError(t *testing.T) {
	client := newTestClient(t, func(t *testing.T, req testRequest) testResponse {
		return testResponse{
			Error: &JSONRPCError{
				Code:    -32700,
				Message: "parse error",
			},
		}
	})

	_, err := client.DaemonStatus(context.Background())
	var rpcErr *JSONRPCError
	if !errors.As(err, &rpcErr) {
		t.Fatalf("expected JSONRPCError, got %T %v", err, err)
	}
	if rpcErr.Code != -32700 {
		t.Fatalf("code = %d", rpcErr.Code)
	}
}

func TestContextDeadlineIsApplied(t *testing.T) {
	client := New("bat.sock")
	client.Timeout = time.Millisecond
	client.DialContext = func(ctx context.Context, network string, address string) (net.Conn, error) {
		<-ctx.Done()
		return nil, ctx.Err()
	}
	ctx, cancel := context.WithTimeout(context.Background(), time.Millisecond)
	defer cancel()

	_, err := client.DaemonStatus(ctx)
	if err == nil {
		t.Fatal("expected dial error")
	}
}