From 95de99104d952b6c05672aca3640f538691f832a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alja=C5=BE=20Mur=20Er=C5=BEen?= <aljaz@edgedb.com>
Date: Thu, 18 Apr 2024 17:21:22 +0200
Subject: [PATCH] Update bigdecimal and add implement Display for Decimal

---
 edgedb-protocol/Cargo.toml          |  2 +-
 edgedb-protocol/src/model/bignum.rs | 61 +++++++++++++++++++++++++++--
 edgedb-tokio/tests/func/client.rs   | 38 ++++++++++++++++++
 3 files changed, 97 insertions(+), 4 deletions(-)

diff --git a/edgedb-protocol/Cargo.toml b/edgedb-protocol/Cargo.toml
index 936dbeb0..24a9ee6a 100644
--- a/edgedb-protocol/Cargo.toml
+++ b/edgedb-protocol/Cargo.toml
@@ -17,7 +17,7 @@ snafu = {version="0.8.0"}
 uuid = "1.1.2"
 num-bigint = {version="0.4.3", optional=true}
 num-traits = {version="0.2.10", optional=true}
-bigdecimal = {version="0.3.0", optional=true}
+bigdecimal = {version="0.4.0", optional=true}
 chrono = {version="0.4.23", optional=true, features=["std"], default-features=false}
 edgedb-errors = {path = "../edgedb-errors", version = "0.4.0" }
 bitflags = "2.4.0"
diff --git a/edgedb-protocol/src/model/bignum.rs b/edgedb-protocol/src/model/bignum.rs
index 5b30409f..2c5ca068 100644
--- a/edgedb-protocol/src/model/bignum.rs
+++ b/edgedb-protocol/src/model/bignum.rs
@@ -1,3 +1,5 @@
+use std::fmt::Write;
+
 #[cfg(feature = "num-bigint")]
 mod num_bigint_interop;
 
@@ -146,9 +148,58 @@ impl Decimal {
     }
 }
 
+impl std::fmt::Display for Decimal {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        if self.negative {
+            write!(f, "-")?;
+        }
+
+        let mut index = 0;
+
+        // integer part
+        while self.weight - index >= 0 {
+            if let Some(digit) = self.digits.get(index as usize) {
+                if index == 0 {
+                    write!(f, "{}", digit)?;
+                } else {
+                    write!(f, "{:04}", digit)?;
+                }
+                index += 1;
+            } else {
+                break;
+            }
+        }
+        if index == 0 {
+            write!(f, "0")?;
+        }
+
+        // dot
+        write!(f, ".")?;
+
+        // decimal part
+        let mut decimals = self.decimal_digits;
+        while decimals > 0 {
+            if let Some(digit) = self.digits.get(index as usize) {
+                let digit = format!("{digit:04}");
+                let consumed = u16::min(4, decimals);
+                f.write_str(&digit[0..consumed as usize])?;
+                decimals -= consumed;
+                index += 1;
+            } else {
+                break;
+            }
+        }
+        // trailing zeros
+        for _ in 0..decimals {
+            f.write_char('0')?;
+        }
+        Ok(())
+    }
+}
+
 #[cfg(test)]
 #[allow(dead_code)] // used by optional tests
- mod test_helpers{
+mod test_helpers{
     use rand::Rng;
 
     pub fn gen_u64<T: Rng>(rng: &mut T) -> u64 {
@@ -162,6 +213,10 @@ impl Decimal {
         let max = 10_i64.pow(rng.gen_range(0..19));
         rng.gen_range(-max..max)
     }
+
+    pub fn gen_f64<T: Rng>(rng: &mut T) -> f64 {
+        rng.gen::<f64>()
+    }
 }
 
 #[cfg(test)]
@@ -238,7 +293,7 @@ mod test {
     }
 
     #[test]
-    fn display() {
+    fn bigint_display() {
         let cases = [
             0,
             1,
@@ -255,7 +310,7 @@ mod test {
     }
 
     #[test]
-    fn display_rand() {
+    fn bigint_display_rand() {
         use rand::{Rng, SeedableRng, rngs::StdRng};
         let mut rng = StdRng::seed_from_u64(4);
         for _ in 0..1000 {
diff --git a/edgedb-tokio/tests/func/client.rs b/edgedb-tokio/tests/func/client.rs
index 532f40ba..7e6a7344 100644
--- a/edgedb-tokio/tests/func/client.rs
+++ b/edgedb-tokio/tests/func/client.rs
@@ -110,3 +110,41 @@ async fn parallel_queries() -> anyhow::Result<()> {
 
     Ok(())
 }
+
+#[tokio::test]
+async fn big_num() -> anyhow::Result<()> {
+    let client = Client::new(&SERVER.config);
+    client.ensure_connected().await?;
+
+    let res = client
+        .query_required_single::<Value, _>("select 1234567890123456789012345678900000n", &())
+        .await
+        .unwrap();
+    if let Value::BigInt(res) = res {
+        assert_eq!(res.to_string(), "1234567890123456789012345678900000");
+    } else {
+        panic!();
+    }
+
+    let res = client
+        .query_required_single::<Value, _>("select 1234567891234567890.12345678900000n", &())
+        .await
+        .unwrap();
+    if let Value::Decimal(res) = res {
+        assert_eq!(res.to_string(), "1234567891234567890.12345678900000");
+    } else {
+        panic!();
+    }
+
+    let res = client
+        .query_required_single::<Value, _>("select 0.00012n", &())
+        .await
+        .unwrap();
+    if let Value::Decimal(res) = res {
+        assert_eq!(res.to_string(), "0.00012");
+    } else {
+        panic!();
+    }
+
+    Ok(())
+}