package deployer

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

	"github.com/alexei/tinyforge/internal/docker"
	"github.com/alexei/tinyforge/internal/store"
	"github.com/google/uuid"
)

// blueGreenDeploy performs a zero-downtime deployment:
// 1. Start new container (green)
// 2. Health check green
// 3. Swap NPM proxy to point to green
// 4. Stop old container (blue)
//
// If the new container fails health check, it is removed and the old one stays.
func (d *Deployer) blueGreenDeploy(
	ctx context.Context,
	project store.Project,
	stage store.Stage,
	settings store.Settings,
	deployID string,
	imageTag string,
) (string, string, string, error) {
	// Find existing running container for this stage (the "blue" container).
	existing, err := d.store.ListContainersByStageID(stage.ID)
	if err != nil {
		return "", "", "", fmt.Errorf("get existing containers: %w", err)
	}

	var blueContainer *store.Container
	for _, c := range existing {
		if c.State == "running" {
			cCopy := c
			blueContainer = &cCopy
			break
		}
	}

	// Step 1: Pull image.
	if err := d.store.UpdateDeployStatus(deployID, "pulling", ""); err != nil {
		slog.Warn("update deploy status", "error", err)
	}
	d.publishDeployStatus(deployID, project.ID, stage.ID, imageTag, "pulling", "")
	d.logDeploy(deployID, fmt.Sprintf("Blue-green: pulling image %s:%s", project.Image, imageTag), "info")

	authConfig, err := d.buildRegistryAuth(project)
	if err != nil {
		return "", "", "", fmt.Errorf("build registry auth: %w", err)
	}

	if err := d.docker.PullImage(ctx, project.Image, imageTag, authConfig); err != nil {
		return "", "", "", fmt.Errorf("pull image: %w", err)
	}
	d.logDeploy(deployID, "Image pulled successfully", "info")

	// Step 2: Ensure network.
	networkID, err := d.docker.EnsureNetwork(ctx, settings.Network)
	if err != nil {
		return "", "", "", fmt.Errorf("ensure network: %w", err)
	}

	// Step 3: Create and start green container.
	if err := d.store.UpdateDeployStatus(deployID, "starting", ""); err != nil {
		slog.Warn("update deploy status", "error", err)
	}
	d.publishDeployStatus(deployID, project.ID, stage.ID, imageTag, "starting", "")

	instanceID := uuid.New().String()
	subdomain := d.buildSubdomain(project, stage, settings, imageTag)
	workloadID := d.resolveProjectWorkloadID(project.ID)
	containerName := docker.ContainerName(project.Name, stage.Name, imageTag)
	portStr := fmt.Sprintf("%d/tcp", project.Port)
	envVars := d.mergeEnvVars(project, stage.ID)
	mounts := d.computeVolumeMounts(project.ID, project.Name, stage.Name, imageTag, settings.BaseVolumePath)

	containerCfg := docker.ContainerConfig{
		Name:         containerName,
		Image:        project.Image + ":" + imageTag,
		Env:          envVars,
		ExposedPorts: []string{portStr},
		NetworkName:  settings.Network,
		NetworkID:    networkID,
		WorkloadID:   workloadID,
		WorkloadKind: string(store.WorkloadKindProject),
		Role:         stage.Name,
		Mounts:       mounts,
		CpuLimit:     stage.CpuLimit,
		MemoryLimit:  stage.MemoryLimit,
	}

	// Set proxy labels for providers that use Docker labels (e.g., Traefik).
	if stage.EnableProxy {
		fqdn := subdomain + "." + settings.Domain
		if proxyLabels := d.proxy.ContainerLabels(fqdn, project.Port); proxyLabels != nil {
			if containerCfg.Labels == nil {
				containerCfg.Labels = make(map[string]string)
			}
			for k, v := range proxyLabels {
				containerCfg.Labels[k] = v
			}
		}
	}

	d.logDeploy(deployID, fmt.Sprintf("Blue-green: creating green container %s", containerName), "info")
	containerID, err := d.docker.CreateContainer(ctx, containerCfg)
	if err != nil {
		return "", "", instanceID, fmt.Errorf("create container: %w", err)
	}

	// Create container row.
	row, err := d.store.CreateContainer(store.Container{
		ID:           instanceID,
		WorkloadID:   workloadID,
		WorkloadKind: string(store.WorkloadKindProject),
		Role:         stage.Name,
		StageID:      stage.ID,
		ContainerID:  containerID,
		ImageRef:     project.Image + ":" + imageTag,
		ImageTag:     imageTag,
		Host:         "local",
		State:        "stopped",
		Port:         project.Port,
		Subdomain:    subdomain,
	})
	if err != nil {
		return containerID, "", instanceID, fmt.Errorf("create container row: %w", err)
	}
	instanceID = row.ID

	if err := d.store.SetDeployInstanceID(deployID, instanceID); err != nil {
		slog.Warn("link deploy to container", "error", err)
	}

	d.logDeploy(deployID, fmt.Sprintf("Blue-green: starting green container %s", containerName), "info")
	if err := d.docker.StartContainer(ctx, containerID); err != nil {
		return containerID, "", instanceID, fmt.Errorf("start container: %w", err)
	}

	if err := d.store.UpdateContainerState(instanceID, "running"); err != nil {
		slog.Warn("update container state", "error", err)
	}
	row.State = "running"
	d.publishInstanceStatus(instanceID, project.ID, stage.ID, "running")

	// Step 4: Health check the green container.
	if project.Healthcheck != "" {
		if err := d.store.UpdateDeployStatus(deployID, "health_checking", ""); err != nil {
			slog.Warn("update deploy status", "error", err)
		}
		d.publishDeployStatus(deployID, project.ID, stage.ID, imageTag, "health_checking", "")

		healthURL := fmt.Sprintf("http://%s:%d%s", containerName, project.Port, project.Healthcheck)
		d.logDeploy(deployID, fmt.Sprintf("Blue-green: health checking green at %s", healthURL), "info")

		if err := d.health.Check(ctx, healthURL); err != nil {
			return containerID, "", instanceID, fmt.Errorf("health check green: %w", err)
		}
		d.logDeploy(deployID, "Blue-green: green health check passed", "info")
	}

	// Step 5: Swap proxy to green.
	var proxyRouteID string
	if stage.EnableProxy {
		if err := d.store.UpdateDeployStatus(deployID, "configuring_proxy", ""); err != nil {
			slog.Warn("update deploy status", "error", err)
		}
		d.publishDeployStatus(deployID, project.ID, stage.ID, imageTag, "configuring_proxy", "")

		accessListID := settings.NpmAccessListID
		if project.NpmAccessListID > 0 {
			accessListID = project.NpmAccessListID
		}

		proxyRouteID, err = d.configureProxy(ctx, deployID, settings, containerID, containerName, project.Port, subdomain, accessListID)
		if err != nil {
			return containerID, "", instanceID, fmt.Errorf("configure proxy: %w", err)
		}

		row.ProxyRouteID = proxyRouteID
		d.logDeploy(deployID, "Blue-green: proxy swapped to green container", "info")

		// Create/update DNS record for the green container.
		fqdn := subdomain + "." + settings.Domain
		d.ensureDNS(ctx, fqdn, "instance", instanceID, deployID)
	} else {
		d.logDeploy(deployID, "Blue-green: proxy skipped (disabled for this stage)", "info")
	}

	row.Subdomain = subdomain
	if err := d.store.UpdateContainer(row); err != nil {
		slog.Warn("update container with proxy ID", "error", err)
	}

	// Step 6: Stop the blue container.
	if blueContainer != nil {
		d.logDeploy(deployID, fmt.Sprintf("Blue-green: stopping blue container %s (tag: %s)", blueContainer.ID, blueContainer.ImageTag), "info")
		if err := d.removeContainer(ctx, *blueContainer, settings); err != nil {
			// Non-fatal: log but continue. Green is already serving traffic.
			d.logDeploy(deployID, fmt.Sprintf("Blue-green: warning: failed to remove blue container: %v", err), "warn")
		} else {
			d.logDeploy(deployID, "Blue-green: blue container removed", "info")
		}
	}

	return containerID, proxyRouteID, instanceID, nil
}