package agent

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"strings"

	mcpv1 "git.wntrmute.dev/mc/mcp/gen/mcp/v1"
	"git.wntrmute.dev/mc/mcp/internal/registry"
	"git.wntrmute.dev/mc/mcp/internal/runtime"
)

// Deploy deploys a service (or a single component of it) to this node.
func (a *Agent) Deploy(ctx context.Context, req *mcpv1.DeployRequest) (*mcpv1.DeployResponse, error) {
	spec := req.GetService()
	if spec == nil {
		return nil, fmt.Errorf("deploy: missing service spec")
	}

	serviceName := spec.GetName()
	a.Logger.Info("deploying", "service", serviceName)

	if err := ensureService(a.DB, serviceName, spec.GetActive()); err != nil {
		return nil, fmt.Errorf("deploy: ensure service %q: %w", serviceName, err)
	}

	components := spec.GetComponents()
	if target := req.GetComponent(); target != "" {
		var filtered []*mcpv1.ComponentSpec
		for _, cs := range components {
			if cs.GetName() == target {
				filtered = append(filtered, cs)
			}
		}
		components = filtered
	}

	var results []*mcpv1.ComponentResult
	active := spec.GetActive()
	for _, cs := range components {
		result := a.deployComponent(ctx, serviceName, cs, active)
		results = append(results, result)
	}

	return &mcpv1.DeployResponse{Results: results}, nil
}

// deployComponent handles the full deploy lifecycle for a single component.
func (a *Agent) deployComponent(ctx context.Context, serviceName string, cs *mcpv1.ComponentSpec, active bool) *mcpv1.ComponentResult {
	compName := cs.GetName()
	containerName := ContainerNameFor(serviceName, compName)

	desiredState := "running"
	if !active {
		desiredState = "stopped"
	}

	a.Logger.Info("deploying component", "service", serviceName, "component", compName, "desired", desiredState)

	// Convert proto routes to registry routes.
	var regRoutes []registry.Route
	for _, r := range cs.GetRoutes() {
		mode := r.GetMode()
		if mode == "" {
			mode = "l4"
		}
		name := r.GetName()
		if name == "" {
			name = "default"
		}
		regRoutes = append(regRoutes, registry.Route{
			Name:     name,
			Port:     int(r.GetPort()),
			Mode:     mode,
			Hostname: r.GetHostname(),
		})
	}

	regComp := &registry.Component{
		Name:         compName,
		Service:      serviceName,
		Image:        cs.GetImage(),
		Network:      cs.GetNetwork(),
		UserSpec:     cs.GetUser(),
		Restart:      cs.GetRestart(),
		DesiredState: desiredState,
		Version:      runtime.ExtractVersion(cs.GetImage()),
		Ports:        cs.GetPorts(),
		Volumes:      cs.GetVolumes(),
		Cmd:          cs.GetCmd(),
		Routes:       regRoutes,
	}

	if err := ensureComponent(a.DB, regComp); err != nil {
		return &mcpv1.ComponentResult{
			Name:  compName,
			Error: fmt.Sprintf("ensure component: %v", err),
		}
	}

	if err := a.Runtime.Pull(ctx, cs.GetImage()); err != nil {
		return &mcpv1.ComponentResult{
			Name:  compName,
			Error: fmt.Sprintf("pull image: %v", err),
		}
	}

	_ = a.Runtime.Stop(ctx, containerName)   // may not exist yet
	_ = a.Runtime.Remove(ctx, containerName) // may not exist yet

	// Build the container spec. If the component has routes, use route-based
	// port allocation and env injection. Otherwise, fall back to legacy ports.
	runSpec := runtime.ContainerSpec{
		Name:    containerName,
		Image:   cs.GetImage(),
		Network: cs.GetNetwork(),
		User:    cs.GetUser(),
		Restart: cs.GetRestart(),
		Volumes: cs.GetVolumes(),
		Cmd:     cs.GetCmd(),
		Env:     cs.GetEnv(),
	}

	if len(regRoutes) > 0 && a.PortAlloc != nil {
		ports, env, err := a.allocateRoutePorts(serviceName, compName, regRoutes)
		if err != nil {
			return &mcpv1.ComponentResult{
				Name:  compName,
				Error: fmt.Sprintf("allocate route ports: %v", err),
			}
		}
		runSpec.Ports = ports
		runSpec.Env = append(runSpec.Env, env...)
	} else {
		// Legacy: use ports directly from the spec.
		runSpec.Ports = cs.GetPorts()
	}

	if err := a.Runtime.Run(ctx, runSpec); err != nil {
		_ = registry.UpdateComponentState(a.DB, serviceName, compName, "", "removed")
		return &mcpv1.ComponentResult{
			Name:  compName,
			Error: fmt.Sprintf("run container: %v", err),
		}
	}

	// Register routes with mc-proxy after the container is running.
	if len(regRoutes) > 0 && a.Proxy != nil {
		hostPorts, err := registry.GetRouteHostPorts(a.DB, serviceName, compName)
		if err != nil {
			a.Logger.Warn("failed to get host ports for route registration", "service", serviceName, "component", compName, "err", err)
		} else if err := a.Proxy.RegisterRoutes(ctx, serviceName, regRoutes, hostPorts); err != nil {
			a.Logger.Warn("failed to register routes with mc-proxy", "service", serviceName, "component", compName, "err", err)
		}
	}

	if err := registry.UpdateComponentState(a.DB, serviceName, compName, "running", "running"); err != nil {
		a.Logger.Warn("failed to update component state", "service", serviceName, "component", compName, "err", err)
	}

	return &mcpv1.ComponentResult{
		Name:    compName,
		Success: true,
	}
}

// allocateRoutePorts allocates host ports for each route, stores them in
// the registry, and returns the port mappings and env vars for the container.
func (a *Agent) allocateRoutePorts(service, component string, routes []registry.Route) ([]string, []string, error) {
	var ports []string
	var env []string

	for _, r := range routes {
		hostPort, err := a.PortAlloc.Allocate()
		if err != nil {
			return nil, nil, fmt.Errorf("allocate port for route %q: %w", r.Name, err)
		}

		if err := registry.UpdateRouteHostPort(a.DB, service, component, r.Name, hostPort); err != nil {
			a.PortAlloc.Release(hostPort)
			return nil, nil, fmt.Errorf("store host port for route %q: %w", r.Name, err)
		}

		ports = append(ports, fmt.Sprintf("127.0.0.1:%d:%d", hostPort, r.Port))

		if len(routes) == 1 {
			env = append(env, fmt.Sprintf("PORT=%d", hostPort))
		} else {
			envName := "PORT_" + strings.ToUpper(r.Name)
			env = append(env, fmt.Sprintf("%s=%d", envName, hostPort))
		}
	}

	return ports, env, nil
}

// ensureService creates the service if it does not exist, or updates its
// active flag if it does.
func ensureService(db *sql.DB, name string, active bool) error {
	_, err := registry.GetService(db, name)
	if errors.Is(err, sql.ErrNoRows) {
		return registry.CreateService(db, name, active)
	}
	if err != nil {
		return err
	}
	return registry.UpdateServiceActive(db, name, active)
}

// ensureComponent creates the component if it does not exist, or updates its
// spec if it does.
func ensureComponent(db *sql.DB, c *registry.Component) error {
	_, err := registry.GetComponent(db, c.Service, c.Name)
	if errors.Is(err, sql.ErrNoRows) {
		c.ObservedState = "unknown"
		return registry.CreateComponent(db, c)
	}
	if err != nil {
		return err
	}
	return registry.UpdateComponentSpec(db, c)
}