package agent

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

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

// StopService stops all components of a service.
func (a *Agent) StopService(ctx context.Context, req *mcpv1.StopServiceRequest) (*mcpv1.StopServiceResponse, error) {
	a.Logger.Info("StopService", "service", req.GetName())

	if req.GetName() == "" {
		return nil, status.Error(codes.InvalidArgument, "service name is required")
	}

	components, err := registry.ListComponents(a.DB, req.GetName())
	if err != nil {
		return nil, status.Errorf(codes.Internal, "list components: %v", err)
	}

	var results []*mcpv1.ComponentResult
	for _, c := range components {
		containerName := ContainerNameFor(req.GetName(), c.Name)
		r := &mcpv1.ComponentResult{Name: c.Name, Success: true}

		if err := a.Runtime.Stop(ctx, containerName); err != nil {
			a.Logger.Info("stop container (ignored)", "container", containerName, "error", err)
		}

		if err := registry.UpdateComponentState(a.DB, req.GetName(), c.Name, "stopped", "stopped"); err != nil {
			r.Success = false
			r.Error = fmt.Sprintf("update state: %v", err)
		}

		results = append(results, r)
	}

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

// StartService starts all components of a service. If a container already
// exists but is stopped, it is removed first so a fresh one can be created.
func (a *Agent) StartService(ctx context.Context, req *mcpv1.StartServiceRequest) (*mcpv1.StartServiceResponse, error) {
	a.Logger.Info("StartService", "service", req.GetName())

	if req.GetName() == "" {
		return nil, status.Error(codes.InvalidArgument, "service name is required")
	}

	components, err := registry.ListComponents(a.DB, req.GetName())
	if err != nil {
		return nil, status.Errorf(codes.Internal, "list components: %v", err)
	}

	var results []*mcpv1.ComponentResult
	for _, c := range components {
		r := startComponent(ctx, a, req.GetName(), &c)
		results = append(results, r)
	}

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

// RestartService restarts all components of a service by stopping, removing,
// and re-creating each container. The desired_state is not changed.
func (a *Agent) RestartService(ctx context.Context, req *mcpv1.RestartServiceRequest) (*mcpv1.RestartServiceResponse, error) {
	a.Logger.Info("RestartService", "service", req.GetName())

	if req.GetName() == "" {
		return nil, status.Error(codes.InvalidArgument, "service name is required")
	}

	components, err := registry.ListComponents(a.DB, req.GetName())
	if err != nil {
		return nil, status.Errorf(codes.Internal, "list components: %v", err)
	}

	var results []*mcpv1.ComponentResult
	for _, c := range components {
		r := restartComponent(ctx, a, req.GetName(), &c)
		results = append(results, r)
	}

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

// startComponent removes any existing container and runs a fresh one from
// the registry spec, then updates state to running.
func startComponent(ctx context.Context, a *Agent, service string, c *registry.Component) *mcpv1.ComponentResult {
	containerName := ContainerNameFor(service, c.Name)
	r := &mcpv1.ComponentResult{Name: c.Name, Success: true}

	// Remove any pre-existing container; ignore errors for non-existent ones.
	_ = a.Runtime.Stop(ctx, containerName)
	_ = a.Runtime.Remove(ctx, containerName)

	spec := componentToSpec(service, c)
	if err := a.Runtime.Run(ctx, spec); err != nil {
		r.Success = false
		r.Error = fmt.Sprintf("run container: %v", err)
		return r
	}

	if err := registry.UpdateComponentState(a.DB, service, c.Name, "running", "running"); err != nil {
		r.Success = false
		r.Error = fmt.Sprintf("update state: %v", err)
	}
	return r
}

// restartComponent stops, removes, and re-creates a container without
// changing the desired_state in the registry.
func restartComponent(ctx context.Context, a *Agent, service string, c *registry.Component) *mcpv1.ComponentResult {
	containerName := ContainerNameFor(service, c.Name)
	r := &mcpv1.ComponentResult{Name: c.Name, Success: true}

	_ = a.Runtime.Stop(ctx, containerName)
	_ = a.Runtime.Remove(ctx, containerName)

	spec := componentToSpec(service, c)
	if err := a.Runtime.Run(ctx, spec); err != nil {
		r.Success = false
		r.Error = fmt.Sprintf("run container: %v", err)
		_ = registry.UpdateComponentState(a.DB, service, c.Name, "", "stopped")
		return r
	}

	if err := registry.UpdateComponentState(a.DB, service, c.Name, "", "running"); err != nil {
		r.Success = false
		r.Error = fmt.Sprintf("update state: %v", err)
	}
	return r
}

// componentToSpec builds a runtime.ContainerSpec from a registry Component.
func componentToSpec(service string, c *registry.Component) runtime.ContainerSpec {
	return runtime.ContainerSpec{
		Name:    ContainerNameFor(service, c.Name),
		Image:   c.Image,
		Network: c.Network,
		User:    c.UserSpec,
		Restart: c.Restart,
		Ports:   c.Ports,
		Volumes: c.Volumes,
		Cmd:     c.Cmd,
	}
}

// componentExists checks whether a component already exists in the registry.
func componentExists(db *sql.DB, service, name string) bool {
	_, err := registry.GetComponent(db, service, name)
	return err == nil
}