package agent

import (
	"bufio"
	"io"

	mcpv1 "git.wntrmute.dev/mc/mcp/gen/mcp/v1"
	"git.wntrmute.dev/mc/mcp/internal/registry"
	"git.wntrmute.dev/mc/mcp/internal/runtime"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
)

// Logs streams container logs for a service component.
func (a *Agent) Logs(req *mcpv1.LogsRequest, stream mcpv1.McpAgentService_LogsServer) error {
	if req.GetService() == "" {
		return status.Error(codes.InvalidArgument, "service name is required")
	}

	// Resolve component name.
	component := req.GetComponent()
	if component == "" {
		components, err := registry.ListComponents(a.DB, req.GetService())
		if err != nil {
			return status.Errorf(codes.Internal, "list components: %v", err)
		}
		if len(components) == 0 {
			return status.Error(codes.NotFound, "no components found for service")
		}
		component = components[0].Name
	}

	containerName := ContainerNameFor(req.GetService(), component)

	podman, ok := a.Runtime.(*runtime.Podman)
	if !ok {
		return status.Error(codes.Internal, "logs requires podman runtime")
	}

	cmd := podman.Logs(stream.Context(), containerName, int(req.GetTail()), req.GetFollow(), req.GetTimestamps(), req.GetSince())

	a.Logger.Info("running podman logs", "container", containerName, "args", cmd.Args)

	// Podman writes container stdout to its stdout and container stderr
	// to its stderr. Merge both into a single pipe.
	pr, pw := io.Pipe()
	cmd.Stdout = pw
	cmd.Stderr = pw

	if err := cmd.Start(); err != nil {
		pw.Close()
		return status.Errorf(codes.Internal, "start podman logs: %v", err)
	}

	// Close the write end when the command exits so the scanner finishes.
	go func() {
		err := cmd.Wait()
		if err != nil {
			a.Logger.Warn("podman logs exited", "container", containerName, "error", err)
		}
		pw.Close()
	}()

	scanner := bufio.NewScanner(pr)
	for scanner.Scan() {
		if err := stream.Send(&mcpv1.LogsResponse{
			Data: append(scanner.Bytes(), '\n'),
		}); err != nil {
			_ = cmd.Process.Kill()
			return err
		}
	}

	return nil
}