package logx

import (
	"bytes"
	"fmt"
	"os"
	"strings"
	"testing"
)

func TestCappedStaysUnderMax(t *testing.T) {
	f, err := os.CreateTemp("", "logx-capped-*")
	if err != nil {
		t.Fatal(err)
	}
	defer os.Remove(f.Name())

	const max = int64(64)
	w := Capped(f, max)
	for i := 0; i < 50; i++ {
		fmt.Fprintf(w, "line %02d padding\n", i) // 16 bytes each
	}

	fi, err := f.Stat()
	if err != nil {
		t.Fatal(err)
	}
	if fi.Size() > max {
		t.Errorf("file grew to %d bytes, cap is %d", fi.Size(), max)
	}
	data, _ := os.ReadFile(f.Name())
	out := string(data)
	if !strings.Contains(out, "line 49") {
		t.Errorf("newest line must survive trims: %q", out)
	}
	if strings.Contains(out, "line 00") {
		t.Errorf("oldest lines must be trimmed away first: %q", out)
	}
}

func TestCappedTrimsOversizedExistingFile(t *testing.T) {
	f, err := os.CreateTemp("", "logx-capped-*")
	if err != nil {
		t.Fatal(err)
	}
	defer os.Remove(f.Name())

	// Simulate a file left behind by an older, uncapped build.
	for i := 0; i < 10; i++ {
		f.WriteString(strings.Repeat("x", 40) + "\n") // 410 bytes total
	}
	w := Capped(f, 64)
	fmt.Fprint(w, "fresh line\n")

	data, _ := os.ReadFile(f.Name())
	out := string(data)
	if !strings.Contains(out, "fresh line") {
		t.Fatalf("new write must land in the file: %q", out)
	}
	if strings.Contains(out, "xxxx") {
		t.Errorf("old oversized content must be trimmed away: %q", out)
	}
}

func TestCountVerbs(t *testing.T) {
	cases := map[string]int{
		"":            0,
		"no verbs":    0,
		"%% literal":  0,
		"a %":         0, // bare trailing percent is not a verb
		"%s":          1,
		"%s %d %v":    3,
		"-%+ 0.2f%x*": 2,
		"%s %% %d":    2,
	}
	for format, want := range cases {
		if got := countVerbs(format); got != want {
			t.Errorf("countVerbs(%q) = %d, want %d", format, got, want)
		}
	}
}

func TestFMismatchWritesDiagnostic(t *testing.T) {
	var buf bytes.Buffer
	AddSink(&buf)

	F("[t]", "login ok: user=%s region=%d", "nathan") // one verb short
	out := buf.String()
	if !strings.Contains(out, "(MISSING)") {
		t.Fatalf("expected rendered mismatch marker in output, got %q", out)
	}
	if !strings.Contains(out, "LOG-FORMAT-MISMATCH") {
		t.Fatalf("expected diagnostic line, got %q", out)
	}
	if !strings.Contains(out, "logx_test.go:") {
		t.Errorf("diagnostic should name the call site: %q", out)
	}

	buf.Reset()
	F("[t]", "balanced %s and %d", "a", 1) // matched: no diagnostic
	if strings.Contains(buf.String(), "LOG-FORMAT-MISMATCH") {
		t.Fatalf("matched format must not emit a diagnostic, got %q", buf.String())
	}

	buf.Reset()
	F("[t]", "extra arg dropped %s", "a", 2) // more args than verbs
	if !strings.Contains(buf.String(), "LOG-FORMAT-MISMATCH") {
		t.Fatalf("expected diagnostic for extra args, got %q", buf.String())
	}
}

// Regression: F once built its value slice with the prefix only and never
// appended the caller's args, so every line rendered "%!v(MISSING)" while the
// verb/arg balance check (which sees the args at the call site) stayed quiet.
func TestFRenderedArgs(t *testing.T) {
	var buf bytes.Buffer
	AddSink(&buf)

	F("[ffxiv-launcher]", "starting ffxiv-tiny-launcher (%s/%s)", "windows", "amd64")
	out := buf.String()
	if !strings.Contains(out, "(windows/amd64)") {
		t.Fatalf("args must render in the line, got %q", out)
	}
	if strings.Contains(out, "(MISSING)") {
		t.Fatalf("balanced call rendered a missing-arg marker: %q", out)
	}

	buf.Reset()
	F("[t]", "login ok: user=%s region=%d maxex=%v", "nathan", 1, true)
	if !strings.Contains(buf.String(), "user=nathan region=1 maxex=true") {
		t.Fatalf("args must render in the line, got %q", buf.String())
	}
}