Dialectic.Backend/internal/httpapi/handlers/arguments.go

package handlers

import (
	"encoding/json"
	"errors"
	"net/http"

	"github.com/go-chi/chi/v5"

	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/auth"
	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/models"
	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/store"
)

type ArgumentsHandler struct {
	topics    *store.TopicStore
	camps     *store.CampStore
	rounds    *store.RoundStore
	arguments *store.ArgumentStore
}

func NewArgumentsHandler(
	t *store.TopicStore,
	c *store.CampStore,
	r *store.RoundStore,
	a *store.ArgumentStore,
) *ArgumentsHandler {
	return &ArgumentsHandler{topics: t, camps: c, rounds: r, arguments: a}
}

type postArgumentBody struct {
	Content string `json:"content"`
}

// POST /api/topics/{id}/arguments
//
// Agent-only. Caller must be allocated to one of the topic's camps;
// rejected otherwise. Topic must be `debating` (status state machine
// enforces; argument outside that window is meaningless). Content is
// stored as-is (no markdown rendering server-side; frontend renders).
//
// Round: argument is attached to the LATEST open round. Round-advance
// policy is the orchestrator's call (Phase 2D ships with manual/single
// round 0; round bumping logic comes when the rule is decided).
func (h *ArgumentsHandler) Post(w http.ResponseWriter, r *http.Request) {
	caller := auth.FromContext(r.Context())
	if caller.Kind != auth.CallerAgent {
		http.Error(w, "argument posting is agent-only", http.StatusForbidden)
		return
	}
	topicID := chi.URLParam(r, "id")

	topic, err := h.topics.GetByID(r.Context(), topicID)
	if errors.Is(err, store.ErrNotFound) {
		http.Error(w, "topic not found", http.StatusNotFound)
		return
	}
	if err != nil {
		http.Error(w, "lookup failed", http.StatusInternalServerError)
		return
	}
	if topic.Status != models.TopicStatusDebating {
		http.Error(w, "topic not in debate window (status="+string(topic.Status)+")", http.StatusConflict)
		return
	}

	camp, err := h.camps.AgentCampInTopic(r.Context(), topicID, caller.ID)
	if err != nil {
		http.Error(w, "you are not allocated to any camp on this topic", http.StatusForbidden)
		return
	}

	round, err := h.rounds.Latest(r.Context(), topicID)
	if err != nil {
		http.Error(w, "no open round (orchestrator hasn't opened round 0 yet?)", http.StatusConflict)
		return
	}

	var body postArgumentBody
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		http.Error(w, "bad body", http.StatusBadRequest)
		return
	}
	if body.Content == "" {
		http.Error(w, "content required", http.StatusBadRequest)
		return
	}
	const maxContent = 32_000 // arbitrary upper bound; arguments shouldn't be book-length
	if len(body.Content) > maxContent {
		http.Error(w, "content too long", http.StatusRequestEntityTooLarge)
		return
	}

	arg, err := h.arguments.Post(r.Context(), store.PostArgumentInput{
		TopicID: topicID,
		RoundID: round.ID,
		Camp:    camp,
		AgentID: caller.ID,
		Content: body.Content,
	})
	if err != nil {
		http.Error(w, "post failed: "+err.Error(), http.StatusInternalServerError)
		return
	}
	writeJSON(w, http.StatusCreated, arg)
}

// GET /api/topics/{id}/arguments — full transcript in posted order.
// Visibility: anonymous can read for public topics; private requires
// any-auth (enforced upstream by middleware composition).
func (h *ArgumentsHandler) List(w http.ResponseWriter, r *http.Request) {
	topicID := chi.URLParam(r, "id")
	topic, err := h.topics.GetByID(r.Context(), topicID)
	if errors.Is(err, store.ErrNotFound) {
		http.Error(w, "topic not found", http.StatusNotFound)
		return
	}
	if err != nil {
		http.Error(w, "lookup failed", http.StatusInternalServerError)
		return
	}
	caller := auth.FromContext(r.Context())
	if caller.Kind == "" && topic.Visibility != models.VisibilityPublic {
		http.Error(w, "not found", http.StatusNotFound)
		return
	}
	rows, err := h.arguments.ListByTopic(r.Context(), topicID)
	if err != nil {
		http.Error(w, "list failed", http.StatusInternalServerError)
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"arguments": rows, "count": len(rows)})
}