From 7edd5d373b8d5fd74153582e331d8076a7808929 Mon Sep 17 00:00:00 2001
From: Deep Goel <34025930+DeepanshuGoel17@users.noreply.github.com>
Date: Thu, 25 May 2023 18:15:24 +0530
Subject: [PATCH] feat: implement std.maxArray (#696)

---
 builtins.go                            | 37 ++++++++++++++++++++++++++
 linter/internal/types/stdlib.go        |  3 ++-
 testdata/builtinMaxArray.golden        |  1 +
 testdata/builtinMaxArray.jsonnet       |  1 +
 testdata/builtinMaxArray.linter.golden |  0
 5 files changed, 41 insertions(+), 1 deletion(-)
 create mode 100644 testdata/builtinMaxArray.golden
 create mode 100644 testdata/builtinMaxArray.jsonnet
 create mode 100644 testdata/builtinMaxArray.linter.golden

diff --git a/builtins.go b/builtins.go
index 93beace..2d93943 100644
--- a/builtins.go
+++ b/builtins.go
@@ -1953,6 +1953,42 @@ func builtinMinArray(i *interpreter, arguments []value) (value, error) {
 	return minVal, nil
 }
 
+func builtinMaxArray(i *interpreter, arguments []value) (value, error) {
+	arrv := arguments[0]
+	keyFv := arguments[1]
+
+	arr, err := i.getArray(arrv)
+	if err != nil {
+		return nil, err
+	}
+	keyF, err := i.getFunction(keyFv)
+	if err != nil {
+		return nil, err
+	}
+	num := arr.length()
+	if num == 0 {
+		return nil, i.Error("Expected at least one element in array. Got none")
+	}
+	maxVal, err := keyF.call(i, args(arr.elements[0]))
+	if err != nil {
+		return nil, err
+	}
+	for index := 1; index < num; index++ {
+		current, err := keyF.call(i, args(arr.elements[index]))
+		if err != nil {
+			return nil, err
+		}
+		cmp, err := valueCmp(i, maxVal, current)
+		if err != nil {
+			return nil, err
+		}
+		if cmp < 0 {
+			maxVal = current
+		}
+	}
+	return maxVal, nil
+}
+
 func builtinNative(i *interpreter, name value) (value, error) {
 	str, err := i.getString(name)
 	if err != nil {
@@ -2385,6 +2421,7 @@ var funcBuiltins = buildBuiltinMap([]builtin{
 	&unaryBuiltin{name: "decodeUTF8", function: builtinDecodeUTF8, params: ast.Identifiers{"arr"}},
 	&generalBuiltin{name: "sort", function: builtinSort, params: []generalBuiltinParameter{{name: "arr"}, {name: "keyF", defaultValue: functionID}}},
 	&generalBuiltin{name: "minArray", function: builtinMinArray, params: []generalBuiltinParameter{{name: "arr"}, {name: "keyF", defaultValue: functionID}}},
+	&generalBuiltin{name: "maxArray", function: builtinMaxArray, params: []generalBuiltinParameter{{name: "arr"}, {name: "keyF", defaultValue: functionID}}},
 	&unaryBuiltin{name: "native", function: builtinNative, params: ast.Identifiers{"x"}},
 	&unaryBuiltin{name: "sum", function: builtinSum, params: ast.Identifiers{"arr"}},
 	&binaryBuiltin{name: "contains", function: builtinContains, params: ast.Identifiers{"arr", "elem"}},
diff --git a/linter/internal/types/stdlib.go b/linter/internal/types/stdlib.go
index b2322b0..0e3c5e8 100644
--- a/linter/internal/types/stdlib.go
+++ b/linter/internal/types/stdlib.go
@@ -141,7 +141,8 @@ func prepareStdlib(g *typeGraph) {
 		"sort":          g.newFuncType(anyArrayType, []ast.Parameter{required("arr"), optional("keyF")}),
 		"uniq":          g.newFuncType(anyArrayType, []ast.Parameter{required("arr"), optional("keyF")}),
 		"sum":           g.newSimpleFuncType(numberType, "arr"),
-		"minArray":      g.newSimpleFuncType(anyType, "arr"),
+		"minArray":      g.newFuncType(anyArrayType, []ast.Parameter{required("arr"), optional("keyF")}),
+		"maxArray":      g.newFuncType(anyArrayType, []ast.Parameter{required("arr"), optional("keyF")}),
 		"contains":      g.newSimpleFuncType(boolType, "arr", "elem"),
 		"remove":        g.newSimpleFuncType(anyArrayType, "arr", "elem"),
 		"removeAt":      g.newSimpleFuncType(anyArrayType, "arr", "i"),
diff --git a/testdata/builtinMaxArray.golden b/testdata/builtinMaxArray.golden
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/testdata/builtinMaxArray.golden
@@ -0,0 +1 @@
+1
diff --git a/testdata/builtinMaxArray.jsonnet b/testdata/builtinMaxArray.jsonnet
new file mode 100644
index 0000000..c60f9ff
--- /dev/null
+++ b/testdata/builtinMaxArray.jsonnet
@@ -0,0 +1 @@
+std.maxArray([1,-1,0])
\ No newline at end of file
diff --git a/testdata/builtinMaxArray.linter.golden b/testdata/builtinMaxArray.linter.golden
new file mode 100644
index 0000000..e69de29