Add proposal approval api endpoint

Change-Id: I3ab864af51735ee7c484df9c66d0b3ec2f6acb36
diff --git a/server/api/api.go b/server/api/api.go
index fd78ee4..ae0af36 100644
--- a/server/api/api.go
+++ b/server/api/api.go
@@ -13,10 +13,10 @@
 const HealthCheckPath = "/healthcheck"
 
 type API struct {
-	Logger  *log.Logger
-	Root    *gin.Engine
-	APIRoot *gin.RouterGroup // 'api/v1'
-	Auth    *gin.RouterGroup // 'api/v1/auth'
+	Logger   *log.Logger
+	Root     *gin.Engine
+	APIRoot  *gin.RouterGroup // 'api/v1'
+	Proposal *gin.RouterGroup // 'api/v1/proposal'
 }
 
 // Init initializes api
@@ -29,6 +29,7 @@
 	})
 	apiObj.APIRoot = router.Group(APIURLSuffix)
 	apiObj.initHealthCheck()
+	apiObj.initProposal()
 
 	apiObj.Root.NoRoute(func(c *gin.Context) {
 		c.JSON(http.StatusNotFound, "Page not found")
diff --git a/server/api/proposal.go b/server/api/proposal.go
new file mode 100644
index 0000000..2adc126
--- /dev/null
+++ b/server/api/proposal.go
@@ -0,0 +1,43 @@
+package api
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+)
+
+func (apiObj *API) initProposal() {
+	apiObj.Proposal = apiObj.APIRoot.Group("/proposal")
+	apiObj.Proposal.POST("/approve", proposalApprovalHandler)
+}
+
+func proposalApprovalHandler(c *gin.Context) {
+	app, err := getApp(c)
+	if err != nil {
+		responseFormat(c, http.StatusInternalServerError, err.Error())
+		return
+	}
+
+	// Read the raw body for signature validation
+	body, err := c.GetRawData()
+	if err != nil {
+		responseFormat(c, http.StatusBadRequest, "Failed to read request body")
+		return
+	}
+
+	// Get the signature from headers
+	signature := c.GetHeader("X-Hub-Signature-256")
+	if signature == "" {
+		// Fallback to the older signature header
+		signature = c.GetHeader("X-Hub-Signature")
+	}
+
+	err = app.ProposalApproval(body, signature)
+	if err != nil {
+		responseFormat(c, http.StatusBadRequest, fmt.Sprintf("Failed to process webhook: %v", err))
+		return
+	}
+
+	responseFormat(c, http.StatusOK, "Proposal approved successfully")
+}
diff --git a/server/app/proposal.go b/server/app/proposal.go
new file mode 100644
index 0000000..4b2acc4
--- /dev/null
+++ b/server/app/proposal.go
@@ -0,0 +1,26 @@
+package app
+
+import (
+	"fmt"
+
+	"github.com/iomodo/staff/git"
+)
+
+func (a *App) ProposalApproval(body []byte, signature string) error {
+	// Validate the webhook signature
+	if err := git.ValidateSignature(body, signature, a.config.GitHub.WebhookSecret); err != nil {
+		return fmt.Errorf("invalid webhook signature: %w", err)
+	}
+
+	// Process the webhook payload
+	taskID, err := git.ProcessMergeWebhook(body, signature, a.config.GitHub.WebhookSecret)
+	if err != nil {
+		return fmt.Errorf("Failed to process webhook: %w", err)
+	}
+
+	// Log the successful approval
+	a.logger.Info("Proposal approved via webhook",
+		"task_id", taskID,
+	)
+	return nil
+}
diff --git a/server/config.yaml b/server/config.yaml
index 0842f0e..5ce3fec 100644
--- a/server/config.yaml
+++ b/server/config.yaml
@@ -13,6 +13,7 @@
   token: "${GITHUB_TOKEN}"
   owner: "iomodo"  # Replace with your GitHub username
   repo: "staff"   # Replace with your repository name
+  webhook_secret: "${GITHUB_WEBHOOK_SECRET}"  # Secret for webhook signature validation
 
 git:
   repo_path: "/Users/shota/github/staff/"
diff --git a/server/config/config.go b/server/config/config.go
index 1a39c6f..2a39741 100644
--- a/server/config/config.go
+++ b/server/config/config.go
@@ -34,9 +34,10 @@
 
 // GitHubConfig represents GitHub integration configuration
 type GitHubConfig struct {
-	Token string `yaml:"token"`
-	Owner string `yaml:"owner"`
-	Repo  string `yaml:"repo"`
+	Token         string `yaml:"token"`
+	Owner         string `yaml:"owner"`
+	Repo          string `yaml:"repo"`
+	WebhookSecret string `yaml:"webhook_secret"` // Secret for webhook signature validation
 }
 
 // GerritConfig represents Gerrit integration configuration
@@ -118,6 +119,9 @@
 	if repo := os.Getenv("GITHUB_REPO"); repo != "" {
 		config.GitHub.Repo = repo
 	}
+	if webhookSecret := os.Getenv("GITHUB_WEBHOOK_SECRET"); webhookSecret != "" {
+		config.GitHub.WebhookSecret = webhookSecret
+	}
 	if gerritUsername := os.Getenv("GERRIT_USERNAME"); gerritUsername != "" {
 		config.Gerrit.Username = gerritUsername
 	}