Issue 9 chat api (#25)

server/handlers/messages.go

@@ -0,0 +1,174 @@
+package handlers
+
+import (
+	"database/sql"
+	"math"
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+
+	"git.gobha.me/xcaliber/chat-switchboard/database"
+)
+
+// ── Request / Response types ────────────────
+
+type createMessageRequest struct {
+	Role    string `json:"role" binding:"required,oneof=user assistant system"`
+	Content string `json:"content" binding:"required"`
+	Model   string `json:"model,omitempty"`
+}
+
+type messageResponse struct {
+	ID        string  `json:"id"`
+	ChatID    string  `json:"chat_id"`
+	Role      string  `json:"role"`
+	Content   string  `json:"content"`
+	Model     *string `json:"model"`
+	TokensUsed *int   `json:"tokens_used"`
+	CreatedAt string  `json:"created_at"`
+}
+
+// MessageHandler holds dependencies for message endpoints.
+type MessageHandler struct{}
+
+// NewMessageHandler creates a new message handler.
+func NewMessageHandler() *MessageHandler {
+	return &MessageHandler{}
+}
+
+// ── List Messages ───────────────────────────
+
+func (h *MessageHandler) ListMessages(c *gin.Context) {
+	page, perPage, offset := parsePagination(c)
+
+	userID := getUserID(c)
+	chatID := c.Param("id")
+
+	// Verify ownership
+	if !userOwnsChat(c, chatID, userID) {
+		return
+	}
+
+	// Count total messages
+	var total int
+	err := database.DB.QueryRow(
+		`SELECT COUNT(*) FROM chat_messages WHERE chat_id = $1`,
+		chatID,
+	).Scan(&total)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to count messages"})
+		return
+	}
+
+	// Fetch messages (oldest first for conversation display)
+	rows, err := database.DB.Query(`
+		SELECT id, chat_id, role, content, model, tokens_used, created_at
+		FROM chat_messages
+		WHERE chat_id = $1
+		ORDER BY created_at ASC
+		LIMIT $2 OFFSET $3
+	`, chatID, perPage, offset)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to list messages"})
+		return
+	}
+	defer rows.Close()
+
+	messages := make([]messageResponse, 0)
+	for rows.Next() {
+		var msg messageResponse
+		err := rows.Scan(
+			&msg.ID, &msg.ChatID, &msg.Role, &msg.Content,
+			&msg.Model, &msg.TokensUsed, &msg.CreatedAt,
+		)
+		if err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to scan message"})
+			return
+		}
+		messages = append(messages, msg)
+	}
+
+	c.JSON(http.StatusOK, paginatedResponse{
+		Data:       messages,
+		Page:       page,
+		PerPage:    perPage,
+		Total:      total,
+		TotalPages: int(math.Ceil(float64(total) / float64(perPage))),
+	})
+}
+
+// ── Create Message ──────────────────────────
+
+func (h *MessageHandler) CreateMessage(c *gin.Context) {
+	var req createMessageRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	userID := getUserID(c)
+	chatID := c.Param("id")
+
+	// Verify ownership
+	if !userOwnsChat(c, chatID, userID) {
+		return
+	}
+
+	var msg messageResponse
+	err := database.DB.QueryRow(`
+		INSERT INTO chat_messages (chat_id, role, content, model)
+		VALUES ($1, $2, $3, $4)
+		RETURNING id, chat_id, role, content, model, tokens_used, created_at
+	`, chatID, req.Role, req.Content, req.Model).Scan(
+		&msg.ID, &msg.ChatID, &msg.Role, &msg.Content,
+		&msg.Model, &msg.TokensUsed, &msg.CreatedAt,
+	)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to create message"})
+		return
+	}
+
+	// Touch the chat's updated_at so it sorts to top of list
+	_, _ = database.DB.Exec(`UPDATE chats SET updated_at = NOW() WHERE id = $1`, chatID)
+
+	c.JSON(http.StatusCreated, msg)
+}
+
+// ── Regenerate (stub for #8 Chat Engine) ────
+
+func (h *MessageHandler) Regenerate(c *gin.Context) {
+	c.JSON(http.StatusNotImplemented, gin.H{
+		"error": "regenerate requires Chat Engine (ticket #8)",
+	})
+}
+
+// ── Stream (stub for #8 Chat Engine) ────────
+
+func (h *MessageHandler) Stream(c *gin.Context) {
+	c.JSON(http.StatusNotImplemented, gin.H{
+		"error": "streaming requires Chat Engine (ticket #8)",
+	})
+}
+
+// ── Ownership Check ─────────────────────────
+
+func userOwnsChat(c *gin.Context, chatID, userID string) bool {
+	var ownerID string
+	err := database.DB.QueryRow(
+		`SELECT user_id FROM chats WHERE id = $1`, chatID,
+	).Scan(&ownerID)
+
+	if err == sql.ErrNoRows {
+		c.JSON(http.StatusNotFound, gin.H{"error": "chat not found"})
+		return false
+	}
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to verify chat ownership"})
+		return false
+	}
+	if ownerID != userID {
+		c.JSON(http.StatusForbidden, gin.H{"error": "not your chat"})
+		return false
+	}
+	return true
+}