package handler

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

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

type TransactionHandler struct {
	store *store.Store
}

func NewTransactionHandler(s *store.Store) *TransactionHandler {
	return &TransactionHandler{store: s}
}

func (h *TransactionHandler) RegisterRoutes(mux *http.ServeMux) {
	mux.HandleFunc("GET /accounts/{id}/transactions", h.listForAccount)
	mux.HandleFunc("POST /transactions", h.create)
	mux.HandleFunc("GET /transactions/{id}", h.get)
	mux.HandleFunc("PUT /transactions/{id}", h.update)
	mux.HandleFunc("DELETE /transactions/{id}", h.delete)
	mux.HandleFunc("PATCH /transactions/{id}/validate", h.validate)
}

func (h *TransactionHandler) listForAccount(w http.ResponseWriter, r *http.Request) {
	accountID, err := parseID(r)
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid account id")
		return
	}
	f := store.AccountTransactionFilters{
		Validated: parseBoolParam(r, "validated"),
		Pending:   parseBoolParam(r, "pending"),
		From:      parseStringParam(r, "from"),
		To:        parseStringParam(r, "to"),
	}
	txs, err := h.store.ListAccountTransactions(r.Context(), accountID, f)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to list transactions")
		return
	}
	writeJSON(w, http.StatusOK, txs)
}

func (h *TransactionHandler) get(w http.ResponseWriter, r *http.Request) {
	id, err := parseTxID(r)
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid id")
		return
	}
	tx, err := h.store.GetTransaction(r.Context(), id)
	if errors.Is(err, pgx.ErrNoRows) {
		writeError(w, http.StatusNotFound, "transaction not found")
		return
	}
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to get transaction")
		return
	}
	writeJSON(w, http.StatusOK, tx)
}

func (h *TransactionHandler) create(w http.ResponseWriter, r *http.Request) {
	var p store.CreateTransactionParams
	if err := json.NewDecoder(r.Body).Decode(&p); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}
	if p.Label == "" {
		writeError(w, http.StatusBadRequest, "label is required")
		return
	}
	if p.Date == "" {
		writeError(w, http.StatusBadRequest, "date is required")
		return
	}
	tx, err := h.store.CreateTransaction(r.Context(), p)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to create transaction")
		return
	}
	writeJSON(w, http.StatusCreated, tx)
}

func (h *TransactionHandler) update(w http.ResponseWriter, r *http.Request) {
	id, err := parseTxID(r)
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid id")
		return
	}
	var p store.CreateTransactionParams
	if err := json.NewDecoder(r.Body).Decode(&p); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}
	if p.Label == "" {
		writeError(w, http.StatusBadRequest, "label is required")
		return
	}
	tx, err := h.store.UpdateTransaction(r.Context(), id, p)
	if errors.Is(err, pgx.ErrNoRows) {
		writeError(w, http.StatusNotFound, "transaction not found")
		return
	}
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to update transaction")
		return
	}
	writeJSON(w, http.StatusOK, tx)
}

func (h *TransactionHandler) delete(w http.ResponseWriter, r *http.Request) {
	id, err := parseTxID(r)
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid id")
		return
	}
	if err := h.store.DeleteTransaction(r.Context(), id); err != nil {
		writeError(w, http.StatusInternalServerError, "failed to delete transaction")
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

func (h *TransactionHandler) validate(w http.ResponseWriter, r *http.Request) {
	id, err := parseTxID(r)
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid id")
		return
	}
	var body struct {
		Validated bool `json:"validated"`
	}
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}
	tx, err := h.store.SetValidated(r.Context(), id, body.Validated)
	if errors.Is(err, pgx.ErrNoRows) {
		writeError(w, http.StatusNotFound, "transaction not found")
		return
	}
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to update transaction")
		return
	}
	writeJSON(w, http.StatusOK, tx)
}

func parseTxID(r *http.Request) (int64, error) {
	v, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	return v, err
}

func parseIntParam(r *http.Request, key string) *int32 {
	v := r.URL.Query().Get(key)
	if v == "" {
		return nil
	}
	n, err := strconv.Atoi(v)
	if err != nil {
		return nil
	}
	i := int32(n)
	return &i
}

func parseBoolParam(r *http.Request, key string) *bool {
	v := r.URL.Query().Get(key)
	if v == "" {
		return nil
	}
	b := v == "true"
	return &b
}

func parseStringParam(r *http.Request, key string) *string {
	v := r.URL.Query().Get(key)
	if v == "" {
		return nil
	}
	return &v
}