From 9f0324cbc1dfd44ab18dd4e73b65f261b433cd8b Mon Sep 17 00:00:00 2001
From: Lilit0x <baasisek01@gmail.com>
Date: Sat, 9 Sep 2023 20:09:14 +0100
Subject: [PATCH 1/2] chore: replace string function

---
 crates/gitql-ast/src/function.rs | 28 ++++++++++++++++++++++++++++
 docs/function/functions.md       |  2 ++
 2 files changed, 30 insertions(+)

diff --git a/crates/gitql-ast/src/function.rs b/crates/gitql-ast/src/function.rs
index 7134ad79..9cd6000a 100644
--- a/crates/gitql-ast/src/function.rs
+++ b/crates/gitql-ast/src/function.rs
@@ -29,6 +29,7 @@ lazy_static! {
         map.insert("left", text_left);
         map.insert("datalength", text_datalength);
         map.insert("char", text_char);
+        map.insert("replace", text_replace);
 
         // Date functions
         map.insert("current_date", date_current_date);
@@ -133,6 +134,13 @@ lazy_static! {
                 result: DataType::Text,
             },
         );
+        map.insert(
+            "replace",
+            Prototype {
+                parameters: vec![DataType::Text, DataType::Text, DataType::Text],
+                result: DataType::Text,
+            },
+        );
 
         // Date functions
         map.insert(
@@ -242,6 +250,26 @@ fn text_char(inputs: Vec<Value>) -> Value {
     return Value::Text("".to_string());
 }
 
+fn text_replace(inputs: Vec<Value>) -> Value {
+    let text = inputs[0].as_text();
+    let old_string = inputs[1].as_text();
+    let new_string = inputs[2].as_text();
+
+    let mut result = String::new();
+    let mut end = 0;
+    for (begin, matched_part) in text
+        .to_lowercase()
+        .match_indices(&old_string.to_lowercase())
+    {
+        result.push_str(&text.get(end..begin).unwrap());
+        result.push_str(&new_string);
+        end = begin + matched_part.len();
+    }
+    result.push_str(&text.get(end..text.len()).unwrap());
+
+    return Value::Text(result);
+}
+
 // Date functions
 
 fn date_current_date(_inputs: Vec<Value>) -> Value {
diff --git a/docs/function/functions.md b/docs/function/functions.md
index 90096d43..740f62f7 100644
--- a/docs/function/functions.md
+++ b/docs/function/functions.md
@@ -18,6 +18,7 @@ note that all functions names are case-insensitive.
 | LEFT       | Text, Number | Text   | Extracts a number of characters from a string (starting from left). |
 | DATALENGTH | Text         | Number | Returns the number of bytes used to represent an expression.        |
 | CHAR       | Number       | Text   | Returns the character based on the ASCII code.                      |
+| REPLACE    | Text, Text, Text | Text  | Replaces all occurrences of a substring within a string, with a new substring. |
 
 ### String functions samples
 
@@ -32,6 +33,7 @@ SELECT name, ASCII(name) AS firstCharAscii FROM commits
 SELECT LEFT("AmrDeveloper", 3) AS extract
 SELECT DATALENGTH("AmrDeveloper") as bytelength
 SELECT CHAR(345) AS code
+SELECT REPLACE("ABC ABC ABC", "a", "c") as replacedText
 ```
 
 ### Date functions

From cf944a79cf49c2f4ed193e38d2b352e995248121 Mon Sep 17 00:00:00 2001
From: Amr Hesham <amr96@programmer.net>
Date: Tue, 12 Sep 2023 09:37:55 +0300
Subject: [PATCH 2/2] Format functions in function.rs

---
 crates/gitql-ast/src/function.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crates/gitql-ast/src/function.rs b/crates/gitql-ast/src/function.rs
index ba3da1ed..09a2c2fc 100644
--- a/crates/gitql-ast/src/function.rs
+++ b/crates/gitql-ast/src/function.rs
@@ -277,7 +277,7 @@ fn text_replace(inputs: Vec<Value>) -> Value {
     return Value::Text(result);
   }
 
-  fn text_substring(inputs: Vec<Value>) -> Value {
+fn text_substring(inputs: Vec<Value>) -> Value {
     let text = inputs[0].as_text();
     //according to the specs, a stirng starts at position 1.
     //but in Rust, the index of a string starts from 0