package fejkdata

import (
	"fmt"
	"strings"
	"testing"
	"testing/fstest"
)

// One Fake call descends depth levels: each level's "a" is the next template down.
func nestedJSON(depth int) string {
	s := `"leaf"`
	for i := 0; i < depth; i++ {
		s = fmt.Sprintf(`{"format":"{a}","a":%s}`, s)
	}
	return s
}

// One Fake call expands n sibling tokens.
func wideTokenJSON(n int) string {
	var toks, fields strings.Builder
	for i := 0; i < n; i++ {
		fmt.Fprintf(&toks, "{f%d}", i)
		if i > 0 {
			fields.WriteByte(',')
		}
		fmt.Fprintf(&fields, `"f%d":"x"`, i)
	}
	return fmt.Sprintf(`{"format":"%s",%s}`, toks.String(), fields.String())
}

func TestNoRenderAllocRegression(t *testing.T) {
	shapes := []struct {
		name string
		json string
		base float64
	}{
		{"nested depth 25", nestedJSON(25), 27},
		{"nested depth 100", nestedJSON(100), 102},
		{"wide 500 tokens", wideTokenJSON(500), 9},
	}
	for _, s := range shapes {
		f, err := New(WithoutShippedData(), WithDataFS(fstest.MapFS{"x.json": {Data: []byte(s.json)}}))
		if err != nil {
			t.Fatalf("New(%s): %v", s.name, err)
		}
		allocs := testing.AllocsPerRun(10000, func() { f.Fake("x") })
		if allocs > s.base*1.10 {
			t.Errorf("%s: %.1f allocs/op regressed past %.1f (baseline %.1f + 10%%); bump the baseline only as a deliberate change", s.name, allocs, s.base*1.10, s.base)
		}
	}
}

func BenchmarkNestedDepth25(b *testing.B)  { benchPath(b, tmpData(b, "deep", nestedJSON(25)), "deep") }
func BenchmarkNestedDepth100(b *testing.B) { benchPath(b, tmpData(b, "deep", nestedJSON(100)), "deep") }
func BenchmarkWideTokens100(b *testing.B) {
	benchPath(b, tmpData(b, "wide", wideTokenJSON(100)), "wide")
}
func BenchmarkWideTokens500(b *testing.B) {
	benchPath(b, tmpData(b, "wide", wideTokenJSON(500)), "wide")
}