From 3ace3f0e158e84d3a831d089acb93a1eb20fac24 Mon Sep 17 00:00:00 2001
From: Taylan Bal <taylanbal50@gmail.com>
Date: Sat, 29 Aug 2026 03:12:07 +0300
Subject: [PATCH] feat(chain): add reusable chain_id query-param parser

Adds ParseChainIDParam to pkg/chain, a shared uint64 parser for the
chain_id query param handled two different ways across services: an
empty value always means "all chains" (0, nil), while a present
literal "0" is either rejected as malformed by default or accepted
via the allowZero flag, matching each caller's existing semantics.
Consolidates the parsing logic that currently exists as two
near-duplicate implementations.

Refs #141

Signed-off-by: Taylan Bal <taylanbal50@gmail.com>
---
 pkg/chain/chain.go      | 18 ++++++++++++++++++
 pkg/chain/chain_test.go | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/pkg/chain/chain.go b/pkg/chain/chain.go
index b04ce3b..e9fadc2 100644
--- a/pkg/chain/chain.go
+++ b/pkg/chain/chain.go
@@ -3,6 +3,7 @@ package chain
 import (
 	"errors"
 	"fmt"
+	"strconv"
 	"strings"
 )
 
@@ -75,3 +76,20 @@ func ChainFromInt(chainID uint64) (Chain, error) {
 	}
 	return "", fmt.Errorf("unknown chain ID: %d", chainID)
 }
+
+// ParseChainIDParam parses a chain_id query param. Empty means 0 ("all chains").
+// A literal 0 is rejected unless allowZero is true.
+func ParseChainIDParam(raw string, allowZero bool) (uint64, error) {
+	s := strings.TrimSpace(raw)
+	if s == "" {
+		return 0, nil
+	}
+	id, err := strconv.ParseUint(s, 10, 64)
+	if err != nil {
+		return 0, fmt.Errorf("invalid chain_id %q: %w", raw, err)
+	}
+	if id == 0 && !allowZero {
+		return 0, errors.New("chain_id must be a non-zero uint64")
+	}
+	return id, nil
+}
diff --git a/pkg/chain/chain_test.go b/pkg/chain/chain_test.go
index 3f39321..91e2b3a 100644
--- a/pkg/chain/chain_test.go
+++ b/pkg/chain/chain_test.go
@@ -70,3 +70,42 @@ func TestGenesisTime(t *testing.T) {
 	_, ok := chain.GenesisTime("unknown")
 	require.False(t, ok)
 }
+
+func TestParseChainIDParam(t *testing.T) {
+	cases := []struct {
+		raw       string
+		allowZero bool
+		want      uint64
+		wantErr   bool
+	}{
+		{"", false, 0, false},
+		{"   ", false, 0, false},
+		{"1", false, 1, false},
+		{" 1 ", false, 1, false},
+		{"18446744073709551615", false, 18446744073709551615, false},
+		{"0", false, 0, true},
+		{"00", false, 0, true},
+		{"-1", false, 0, true},
+		{"+1", false, 0, true},
+		{"abc", false, 0, true},
+		{"1.0", false, 0, true},
+		{"18446744073709551616", false, 0, true},
+		{"", true, 0, false},
+		{"0", true, 0, false},
+		{"00", true, 0, false},
+		{"1", true, 1, false},
+		{"-1", true, 0, true},
+		{"abc", true, 0, true},
+		{"18446744073709551616", true, 0, true},
+	}
+	for _, c := range cases {
+		id, err := chain.ParseChainIDParam(c.raw, c.allowZero)
+		if c.wantErr {
+			require.Error(t, err)
+			require.Equal(t, uint64(0), id)
+			continue
+		}
+		require.NoError(t, err)
+		require.Equal(t, c.want, id)
+	}
+}