// SPDX-License-Identifier: GPL-2.0-or-later
// Copyright (C) 2026 Bryan Joshua Pedini

package main

import (
	"context"
	"fmt"
	"log/slog"
	"time"

	"github.com/moby/moby/api/types/container"
	"github.com/moby/moby/client"
)

// dockerHost is the Docker Engine endpoint used in production
const dockerHost = "unix:///var/run/docker.sock"

// dockerListTimeout bounds every container-list call (the SDK has no default timeout)
const dockerListTimeout = 10 * time.Second

// ContainerLister is the narrow Docker dependency of the HTTP layer
type ContainerLister interface {
	ListRunningContainers(ctx context.Context) ([]container.Summary, error)
}

// DockerClient wraps the Docker Engine SDK client
type DockerClient struct {
	cli     *client.Client
	log     *slog.Logger
	timeout time.Duration
}

// NewDockerClient creates a client for the given Engine host (e.g. unix:///var/run/docker.sock)
// The connection is lazy: an absent or inaccessible socket only fails individual requests
func NewDockerClient(host string, log *slog.Logger) (*DockerClient, error) {
	cli, err := client.New(client.WithHost(host))
	if err != nil {
		return nil, fmt.Errorf("create docker client: %w", err)
	}
	return &DockerClient{cli: cli, log: log, timeout: dockerListTimeout}, nil
}

// ListRunningContainers returns the running containers, like `docker ps`
// The result is never nil, so it serializes as [] when empty
func (d *DockerClient) ListRunningContainers(ctx context.Context) ([]container.Summary, error) {
	defer traceFunc(ctx, d.log, "DockerClient.ListRunningContainers")()

	ctx, cancel := context.WithTimeout(ctx, d.timeout)
	defer cancel()

	// All=false: running containers only
	res, err := d.cli.ContainerList(ctx, client.ContainerListOptions{})
	if err != nil {
		return nil, fmt.Errorf("list containers: %w", err)
	}
	items := res.Items
	if items == nil {
		items = []container.Summary{}
	}
	for _, c := range items {
		trace(ctx, d.log, "container listed", "id", c.ID, "names", c.Names, "image", c.Image, "state", c.State)
	}
	return items, nil
}

// Close releases the client's resources
func (d *DockerClient) Close() error {
	return d.cli.Close()
}