package template

import (
	"bytes"
	"reflect"
	"testing"
	"text/template"
)

func TestBuildFuncMapEntriesAreFunctions(t *testing.T) {
	fm := BuildFuncMap()
	if len(fm) < 100 {
		t.Errorf("unexpectedly small func map: %d", len(fm))
	}
	for name, fn := range fm {
		if reflect.TypeOf(fn).Kind() != reflect.Func {
			t.Errorf("%s is not a function", name)
		}
	}
	for _, name := range []string{"toSnakeCase", "sqlToGo", "filterTables", "toJSON", "enumerate", "get", "sortTablesByName", "dict", "seq"} {
		if _, ok := fm[name]; !ok {
			t.Errorf("missing %s", name)
		}
	}
	// Must be accepted by text/template (valid names and signatures).
	if _, err := template.New("x").Funcs(fm).Parse("ok"); err != nil {
		t.Fatalf("funcmap rejected by text/template: %v", err)
	}
}

func TestBuildFuncMapRender(t *testing.T) {
	tests := []struct {
		name, tmpl, want string
	}{
		{"add", `{{add 2 3}}`, "5"},
		{"sub", `{{sub 5 3}}`, "2"},
		{"mul", `{{mul 2 3}}`, "6"},
		{"div", `{{div 6 3}}`, "2"},
		{"div zero", `{{div 6 0}}`, "0"},
		{"mod", `{{mod 7 3}}`, "1"},
		{"mod zero", `{{mod 7 0}}`, "0"},
		{"default nil", `{{default "d" .Missing}}`, "d"},
		{"default set", `{{default "d" "v"}}`, "v"},
		{"dict", `{{get (dict "a" 1) "a"}}`, "1"},
		{"dict odd", `{{if dict "a"}}set{{else}}nil{{end}}`, "nil"},
		{"dict non-string key", `{{if dict 1 2}}set{{else}}nil{{end}}`, "nil"},
		{"list", `{{len (list 1 2 3)}}`, "3"},
		{"seq", `{{range seq 1 3}}{{.}}{{end}}`, "123"},
		{"seq reversed", `{{len (seq 3 1)}}`, "0"},
		{"snake", `{{toSnakeCase "UserName"}}`, "user_name"},
		{"pluralize", `{{pluralize "category"}}`, "categories"},
		{"sqlToGo", `{{sqlToGo "integer" true}}`, ""},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			tpl, err := template.New("t").Funcs(BuildFuncMap()).Parse(tt.tmpl)
			if err != nil {
				t.Fatalf("parse: %v", err)
			}
			var buf bytes.Buffer
			if err := tpl.Execute(&buf, map[string]interface{}{}); err != nil {
				t.Fatalf("execute: %v", err)
			}
			if tt.name == "sqlToGo" {
				if buf.Len() == 0 {
					t.Error("sqlToGo rendered nothing")
				}
				return
			}
			if buf.String() != tt.want {
				t.Errorf("got %q, want %q", buf.String(), tt.want)
			}
		})
	}
}