package handler

import (
	"errors"
	"net/http"
	"time"

	"git.g3e.fr/H6N/account/internal/snapshot"
	"git.g3e.fr/H6N/account/internal/store"
	"github.com/jackc/pgx/v5"
)

func (h *SnapshotHandler) verifyAccountOwner(w http.ResponseWriter, r *http.Request) (int32, int32, bool) {
	ownerID, ok := requireOwner(w, r)
	if !ok {
		return 0, 0, false
	}
	accountID, err := parseID(r)
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid account id")
		return 0, 0, false
	}
	if err := h.engine.Store().VerifyAccountOwner(r.Context(), accountID, ownerID); errors.Is(err, pgx.ErrNoRows) {
		writeError(w, http.StatusNotFound, "account not found")
		return 0, 0, false
	} else if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to verify account")
		return 0, 0, false
	}
	return ownerID, accountID, true
}

type SnapshotHandler struct {
	engine *snapshot.Engine
}

func NewSnapshotHandler(e *snapshot.Engine) *SnapshotHandler {
	return &SnapshotHandler{engine: e}
}

func (h *SnapshotHandler) RegisterRoutes(mux *http.ServeMux) {
	mux.HandleFunc("GET  /accounts/{id}/snapshots",           h.listAccountSnapshots)
	mux.HandleFunc("GET  /accounts/{id}/snapshots/positions", h.listPositionSnapshots)
	mux.HandleFunc("POST /accounts/{id}/snapshots/recompute", h.recomputeAccount)
	mux.HandleFunc("GET  /snapshots/pending",                 h.listPending)
}

// parseDateParam parse un paramètre de query YYYY-MM-DD. Retourne time.Time{} si absent.
func parseDateParam(r *http.Request, key string) (time.Time, error) {
	v := r.URL.Query().Get(key)
	if v == "" {
		return time.Time{}, nil
	}
	return time.Parse("2006-01-02", v)
}

// GET /snapshots/pending
// Liste les comptes de l'owner ayant une invalidation en attente.
func (h *SnapshotHandler) listPending(w http.ResponseWriter, r *http.Request) {
	ownerID, ok := requireOwner(w, r)
	if !ok {
		return
	}
	invalidations, err := h.engine.Store().GetInvalidationsForOwner(r.Context(), ownerID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}

	type row struct {
		AccountID     int32  `json:"account_id"`
		RecomputeFrom string `json:"recompute_from"`
	}
	out := make([]row, 0, len(invalidations))
	for _, inv := range invalidations {
		out = append(out, row{
			AccountID:     inv.AccountID,
			RecomputeFrom: inv.RecomputeFrom.Format("2006-01-02"),
		})
	}
	writeJSON(w, http.StatusOK, out)
}

// GET /accounts/{id}/snapshots?from=YYYY-MM-DD&to=YYYY-MM-DD
// Liste les snapshots agrégés (valeur totale) d'un compte.
// from/to optionnels : sans borne → pas de filtre de ce côté.
func (h *SnapshotHandler) listAccountSnapshots(w http.ResponseWriter, r *http.Request) {
	_, accountID, ok := h.verifyAccountOwner(w, r)
	if !ok {
		return
	}
	from, err := parseDateParam(r, "from")
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid from date")
		return
	}
	to, err := parseDateParam(r, "to")
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid to date")
		return
	}

	rows, err := h.engine.Store().ListAccountSnapshots(r.Context(), accountID, from, to)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	if rows == nil {
		rows = []store.AccountSnapshotRow{}
	}
	writeJSON(w, http.StatusOK, rows)
}

// GET /accounts/{id}/snapshots/positions?from=YYYY-MM-DD&to=YYYY-MM-DD
// Liste les positions détaillées (par instrument) d'un compte.
func (h *SnapshotHandler) listPositionSnapshots(w http.ResponseWriter, r *http.Request) {
	_, accountID, ok := h.verifyAccountOwner(w, r)
	if !ok {
		return
	}
	from, err := parseDateParam(r, "from")
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid from date")
		return
	}
	to, err := parseDateParam(r, "to")
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid to date")
		return
	}

	rows, err := h.engine.Store().ListPositionSnapshots(r.Context(), accountID, from, to)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}
	if rows == nil {
		rows = []store.PositionSnapshotRow{}
	}
	writeJSON(w, http.StatusOK, rows)
}

// POST /accounts/{id}/snapshots/recompute
// Recalcule les snapshots du compte depuis sa date d'invalidation jusqu'à aujourd'hui.
// Retourne 204 si aucune invalidation n'est en attente.
func (h *SnapshotHandler) recomputeAccount(w http.ResponseWriter, r *http.Request) {
	_, accountID, ok := h.verifyAccountOwner(w, r)
	if !ok {
		return
	}

	from, to, err := h.engine.RecomputeAccount(r.Context(), accountID)
	if errors.Is(err, pgx.ErrNoRows) {
		writeError(w, http.StatusNotFound, "account not found")
		return
	}
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}

	if from.IsZero() {
		w.WriteHeader(http.StatusNoContent) // aucune invalidation en attente
		return
	}

	writeJSON(w, http.StatusOK, map[string]any{
		"account_id": accountID,
		"from":       from.Format("2006-01-02"),
		"to":         to.Format("2006-01-02"),
		"status":     "ok",
	})
}