refactor(api): restructured API for type safety, maintainability and docs generation

- These changes makes the API incombatible with previous versions
- Added new types for error handling, success responses, and health checks.
- Updated health check logic to utilize the new types for better clarity and structure.
- Refactored existing handlers to improve response consistency and error handling.
- Updated Makefile to include a new target for generating API types from Swagger.
- Updated "new agent" API to respond an encrypted cert pair

internal/api/v1/agent/create.go

@@ -0,0 +1,103 @@
+package agentapi
+
+import (
+	"fmt"
+	"net/http"
+
+	_ "embed"
+
+	"github.com/gin-gonic/gin"
+	"github.com/yusing/go-proxy/agent/pkg/agent"
+	apitypes "github.com/yusing/go-proxy/internal/api/types"
+)
+
+type NewAgentRequest struct {
+	Name    string `form:"name" validate:"required"`
+	Host    string `form:"host" validate:"required"`
+	Port    int    `form:"port" validate:"required,min=1,max=65535"`
+	Type    string `form:"type" validate:"required,oneof=docker system"`
+	Nightly bool   `form:"nightly" validate:"omitempty"`
+} // @name NewAgentRequest
+
+type NewAgentResponse struct {
+	Compose string          `json:"compose"`
+	CA      PEMPairResponse `json:"ca"`
+	Client  PEMPairResponse `json:"client"`
+} // @name NewAgentResponse
+
+// @x-id				"create"
+// @BasePath		/api/v1
+// @Summary		Create a new agent
+// @Description	Create a new agent and return the docker compose file, encrypted CA and client PEMs
+// @Description	The returned PEMs are encrypted with a random key and will be used for verification when adding a new agent
+// @Tags			agent
+// @Accept			json
+// @Produce		json
+// @Param			request	body		NewAgentRequest	true	"Request"
+// @Success		200		{object}	NewAgentResponse
+// @Failure		400		{object}	apitypes.ErrorResponse
+// @Failure		403		{object}	apitypes.ErrorResponse
+// @Failure		409		{object}	apitypes.ErrorResponse
+// @Failure		500		{object}	apitypes.ErrorResponse
+// @Router			/agent/create [post]
+func Create(c *gin.Context) {
+	var request NewAgentRequest
+	if err := c.ShouldBindQuery(&request); err != nil {
+		c.JSON(http.StatusBadRequest, apitypes.Error("invalid request", err))
+		return
+	}
+	hostport := fmt.Sprintf("%s:%d", request.Host, request.Port)
+	if _, ok := agent.GetAgent(hostport); ok {
+		c.JSON(http.StatusConflict, apitypes.Error("agent already exists"))
+		return
+	}
+
+	var image string
+	if request.Nightly {
+		image = agent.DockerImageNightly
+	} else {
+		image = agent.DockerImageProduction
+	}
+
+	ca, srv, client, err := agent.NewAgent()
+	if err != nil {
+		c.Error(apitypes.InternalServerError(err, "failed to create agent"))
+		return
+	}
+
+	var cfg agent.Generator = &agent.AgentEnvConfig{
+		Name:    request.Name,
+		Port:    request.Port,
+		CACert:  ca.String(),
+		SSLCert: srv.String(),
+	}
+	if request.Type == "docker" {
+		cfg = &agent.AgentComposeConfig{
+			Image:          image,
+			AgentEnvConfig: cfg.(*agent.AgentEnvConfig),
+		}
+	}
+	template, err := cfg.Generate()
+	if err != nil {
+		c.Error(apitypes.InternalServerError(err, "failed to generate agent config"))
+		return
+	}
+
+	key := getEncryptionKey()
+	encCA, err := ca.Encrypt(key)
+	if err != nil {
+		c.Error(apitypes.InternalServerError(err, "failed to encrypt CA PEMs"))
+		return
+	}
+	encClient, err := client.Encrypt(key)
+	if err != nil {
+		c.Error(apitypes.InternalServerError(err, "failed to encrypt client PEMs"))
+		return
+	}
+
+	c.JSON(http.StatusOK, NewAgentResponse{
+		Compose: template,
+		CA:      toPEMPairResponse(encCA),
+		Client:  toPEMPairResponse(encClient),
+	})
+}