// Package docker provides Docker client functionality.
package docker

import (
	"context"
	"errors"
	"fmt"
	"io"
	"log/slog"
	"os"
	"path/filepath"

	"github.com/docker/docker/api/types"
	"github.com/docker/docker/api/types/container"
	"github.com/docker/docker/api/types/mount"
	"github.com/docker/docker/api/types/network"
	"github.com/docker/docker/client"
	"github.com/docker/docker/pkg/archive"
	"go.uber.org/fx"

	"git.eeqj.de/sneak/upaas/internal/config"
	"git.eeqj.de/sneak/upaas/internal/logger"
)

// sshKeyPermissions is the file permission for SSH private keys.
const sshKeyPermissions = 0o600

// stopTimeoutSeconds is the timeout for stopping containers.
const stopTimeoutSeconds = 10

// ErrNotConnected is returned when Docker client is not connected.
var ErrNotConnected = errors.New("docker client not connected")

// ErrGitCloneFailed is returned when git clone fails.
var ErrGitCloneFailed = errors.New("git clone failed")

// Params contains dependencies for Client.
type Params struct {
	fx.In

	Logger *logger.Logger
	Config *config.Config
}

// Client wraps the Docker client.
type Client struct {
	docker *client.Client
	log    *slog.Logger
	params *Params
}

// New creates a new Docker Client.
func New(lifecycle fx.Lifecycle, params Params) (*Client, error) {
	dockerClient := &Client{
		log:    params.Logger.Get(),
		params: &params,
	}

	// For testing, if lifecycle is nil, skip connection (tests mock Docker)
	if lifecycle == nil {
		return dockerClient, nil
	}

	lifecycle.Append(fx.Hook{
		OnStart: func(ctx context.Context) error {
			return dockerClient.connect(ctx)
		},
		OnStop: func(_ context.Context) error {
			return dockerClient.close()
		},
	})

	return dockerClient, nil
}

// IsConnected returns true if the Docker client is connected.
func (c *Client) IsConnected() bool {
	return c.docker != nil
}

// BuildImageOptions contains options for building an image.
type BuildImageOptions struct {
	ContextDir     string
	DockerfilePath string
	Tags           []string
}

// BuildImage builds a Docker image from a context directory.
func (c *Client) BuildImage(
	ctx context.Context,
	opts BuildImageOptions,
) (string, error) {
	if c.docker == nil {
		return "", ErrNotConnected
	}

	c.log.Info(
		"building docker image",
		"context", opts.ContextDir,
		"dockerfile", opts.DockerfilePath,
	)

	imageID, err := c.performBuild(ctx, opts)
	if err != nil {
		return "", err
	}

	return imageID, nil
}

// CreateContainerOptions contains options for creating a container.
type CreateContainerOptions struct {
	Name    string
	Image   string
	Env     map[string]string
	Labels  map[string]string
	Volumes []VolumeMount
	Network string
}

// VolumeMount represents a volume mount.
type VolumeMount struct {
	HostPath      string
	ContainerPath string
	ReadOnly      bool
}

// CreateContainer creates a new container.
func (c *Client) CreateContainer(
	ctx context.Context,
	opts CreateContainerOptions,
) (string, error) {
	if c.docker == nil {
		return "", ErrNotConnected
	}

	c.log.Info("creating container", "name", opts.Name, "image", opts.Image)

	// Convert env map to slice
	envSlice := make([]string, 0, len(opts.Env))

	for key, val := range opts.Env {
		envSlice = append(envSlice, key+"="+val)
	}

	// Convert volumes to mounts
	mounts := make([]mount.Mount, 0, len(opts.Volumes))

	for _, vol := range opts.Volumes {
		mounts = append(mounts, mount.Mount{
			Type:     mount.TypeBind,
			Source:   vol.HostPath,
			Target:   vol.ContainerPath,
			ReadOnly: vol.ReadOnly,
		})
	}

	// Create container
	resp, err := c.docker.ContainerCreate(ctx,
		&container.Config{
			Image:  opts.Image,
			Env:    envSlice,
			Labels: opts.Labels,
		},
		&container.HostConfig{
			Mounts:      mounts,
			NetworkMode: container.NetworkMode(opts.Network),
			RestartPolicy: container.RestartPolicy{
				Name: container.RestartPolicyUnlessStopped,
			},
		},
		&network.NetworkingConfig{},
		nil,
		opts.Name,
	)
	if err != nil {
		return "", fmt.Errorf("failed to create container: %w", err)
	}

	return resp.ID, nil
}

// StartContainer starts a container.
func (c *Client) StartContainer(ctx context.Context, containerID string) error {
	if c.docker == nil {
		return ErrNotConnected
	}

	c.log.Info("starting container", "id", containerID)

	err := c.docker.ContainerStart(ctx, containerID, container.StartOptions{})
	if err != nil {
		return fmt.Errorf("failed to start container: %w", err)
	}

	return nil
}

// StopContainer stops a container.
func (c *Client) StopContainer(ctx context.Context, containerID string) error {
	if c.docker == nil {
		return ErrNotConnected
	}

	c.log.Info("stopping container", "id", containerID)

	timeout := stopTimeoutSeconds

	err := c.docker.ContainerStop(ctx, containerID, container.StopOptions{Timeout: &timeout})
	if err != nil {
		return fmt.Errorf("failed to stop container: %w", err)
	}

	return nil
}

// RemoveContainer removes a container.
func (c *Client) RemoveContainer(
	ctx context.Context,
	containerID string,
	force bool,
) error {
	if c.docker == nil {
		return ErrNotConnected
	}

	c.log.Info("removing container", "id", containerID, "force", force)

	err := c.docker.ContainerRemove(ctx, containerID, container.RemoveOptions{Force: force})
	if err != nil {
		return fmt.Errorf("failed to remove container: %w", err)
	}

	return nil
}

// ContainerLogs returns the logs for a container.
func (c *Client) ContainerLogs(
	ctx context.Context,
	containerID string,
	tail string,
) (string, error) {
	if c.docker == nil {
		return "", ErrNotConnected
	}

	opts := container.LogsOptions{
		ShowStdout: true,
		ShowStderr: true,
		Tail:       tail,
	}

	reader, err := c.docker.ContainerLogs(ctx, containerID, opts)
	if err != nil {
		return "", fmt.Errorf("failed to get container logs: %w", err)
	}

	defer func() {
		closeErr := reader.Close()
		if closeErr != nil {
			c.log.Error("failed to close log reader", "error", closeErr)
		}
	}()

	logs, err := io.ReadAll(reader)
	if err != nil {
		return "", fmt.Errorf("failed to read container logs: %w", err)
	}

	return string(logs), nil
}

// IsContainerRunning checks if a container is running.
func (c *Client) IsContainerRunning(
	ctx context.Context,
	containerID string,
) (bool, error) {
	if c.docker == nil {
		return false, ErrNotConnected
	}

	inspect, err := c.docker.ContainerInspect(ctx, containerID)
	if err != nil {
		return false, fmt.Errorf("failed to inspect container: %w", err)
	}

	return inspect.State.Running, nil
}

// IsContainerHealthy checks if a container is healthy.
func (c *Client) IsContainerHealthy(
	ctx context.Context,
	containerID string,
) (bool, error) {
	if c.docker == nil {
		return false, ErrNotConnected
	}

	inspect, err := c.docker.ContainerInspect(ctx, containerID)
	if err != nil {
		return false, fmt.Errorf("failed to inspect container: %w", err)
	}

	// If no health check defined, consider running as healthy
	if inspect.State.Health == nil {
		return inspect.State.Running, nil
	}

	return inspect.State.Health.Status == "healthy", nil
}

// cloneConfig holds configuration for a git clone operation.
type cloneConfig struct {
	repoURL       string
	branch        string
	sshPrivateKey string
	destDir       string
	keyFile       string
}

// CloneRepo clones a git repository using SSH.
func (c *Client) CloneRepo(
	ctx context.Context,
	repoURL, branch, sshPrivateKey, destDir string,
) error {
	if c.docker == nil {
		return ErrNotConnected
	}

	c.log.Info("cloning repository", "url", repoURL, "branch", branch, "dest", destDir)

	cfg := &cloneConfig{
		repoURL:       repoURL,
		branch:        branch,
		sshPrivateKey: sshPrivateKey,
		destDir:       destDir,
		keyFile:       filepath.Join(destDir, ".deploy_key"),
	}

	return c.performClone(ctx, cfg)
}

func (c *Client) performBuild(
	ctx context.Context,
	opts BuildImageOptions,
) (string, error) {
	// Create tar archive of build context
	tarArchive, err := archive.TarWithOptions(opts.ContextDir, &archive.TarOptions{})
	if err != nil {
		return "", fmt.Errorf("failed to create build context: %w", err)
	}

	defer func() {
		closeErr := tarArchive.Close()
		if closeErr != nil {
			c.log.Error("failed to close tar archive", "error", closeErr)
		}
	}()

	// Build image
	resp, err := c.docker.ImageBuild(ctx, tarArchive, types.ImageBuildOptions{
		Dockerfile: opts.DockerfilePath,
		Tags:       opts.Tags,
		Remove:     true,
		NoCache:    false,
	})
	if err != nil {
		return "", fmt.Errorf("failed to build image: %w", err)
	}

	defer func() {
		closeErr := resp.Body.Close()
		if closeErr != nil {
			c.log.Error("failed to close response body", "error", closeErr)
		}
	}()

	// Read build output (logs to stdout for now)
	_, err = io.Copy(os.Stdout, resp.Body)
	if err != nil {
		return "", fmt.Errorf("failed to read build output: %w", err)
	}

	// Get image ID
	if len(opts.Tags) > 0 {
		inspect, _, inspectErr := c.docker.ImageInspectWithRaw(ctx, opts.Tags[0])
		if inspectErr != nil {
			return "", fmt.Errorf("failed to inspect image: %w", inspectErr)
		}

		return inspect.ID, nil
	}

	return "", nil
}

func (c *Client) performClone(ctx context.Context, cfg *cloneConfig) error {
	// Write SSH key to temp file
	err := os.WriteFile(cfg.keyFile, []byte(cfg.sshPrivateKey), sshKeyPermissions)
	if err != nil {
		return fmt.Errorf("failed to write SSH key: %w", err)
	}

	defer func() {
		removeErr := os.Remove(cfg.keyFile)
		if removeErr != nil {
			c.log.Error("failed to remove SSH key file", "error", removeErr)
		}
	}()

	containerID, err := c.createGitContainer(ctx, cfg)
	if err != nil {
		return err
	}

	defer func() {
		_ = c.docker.ContainerRemove(ctx, containerID, container.RemoveOptions{Force: true})
	}()

	return c.runGitClone(ctx, containerID)
}

func (c *Client) createGitContainer(
	ctx context.Context,
	cfg *cloneConfig,
) (string, error) {
	gitSSHCmd := "ssh -i /keys/deploy_key -o StrictHostKeyChecking=no"

	resp, err := c.docker.ContainerCreate(ctx,
		&container.Config{
			Image: "alpine/git:latest",
			Cmd: []string{
				"clone", "--depth", "1", "--branch", cfg.branch, cfg.repoURL, "/repo",
			},
			Env:        []string{"GIT_SSH_COMMAND=" + gitSSHCmd},
			WorkingDir: "/",
		},
		&container.HostConfig{
			Mounts: []mount.Mount{
				{Type: mount.TypeBind, Source: cfg.destDir, Target: "/repo"},
				{
					Type:     mount.TypeBind,
					Source:   cfg.keyFile,
					Target:   "/keys/deploy_key",
					ReadOnly: true,
				},
			},
		},
		nil,
		nil,
		"",
	)
	if err != nil {
		return "", fmt.Errorf("failed to create git container: %w", err)
	}

	return resp.ID, nil
}

func (c *Client) runGitClone(ctx context.Context, containerID string) error {
	err := c.docker.ContainerStart(ctx, containerID, container.StartOptions{})
	if err != nil {
		return fmt.Errorf("failed to start git container: %w", err)
	}

	statusCh, errCh := c.docker.ContainerWait(ctx, containerID, container.WaitConditionNotRunning)

	select {
	case err := <-errCh:
		return fmt.Errorf("error waiting for git container: %w", err)
	case status := <-statusCh:
		if status.StatusCode != 0 {
			logs, _ := c.ContainerLogs(ctx, containerID, "100")

			return fmt.Errorf(
				"%w with status %d: %s",
				ErrGitCloneFailed,
				status.StatusCode,
				logs,
			)
		}
	}

	return nil
}

func (c *Client) connect(ctx context.Context) error {
	opts := []client.Opt{
		client.FromEnv,
		client.WithAPIVersionNegotiation(),
	}

	if c.params.Config.DockerHost != "" {
		opts = append(opts, client.WithHost(c.params.Config.DockerHost))
	}

	docker, err := client.NewClientWithOpts(opts...)
	if err != nil {
		return fmt.Errorf("failed to create Docker client: %w", err)
	}

	// Test connection
	_, err = docker.Ping(ctx)
	if err != nil {
		return fmt.Errorf("failed to ping Docker: %w", err)
	}

	c.docker = docker
	c.log.Info("docker client connected")

	return nil
}

func (c *Client) close() error {
	if c.docker != nil {
		err := c.docker.Close()
		if err != nil {
			return fmt.Errorf("failed to close docker client: %w", err)
		}
	}

	return nil
}