package email

import (
	"testing"

	"github.com/stretchr/testify/assert"
	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"go.uber.org/zap/zaptest/observer"
)

// clearAllSMTPEnv zeroes every SMTP-related env var (canonical + deprecated)
// so each test starts from a known blank slate. t.Setenv guarantees restore.
func clearAllSMTPEnv(t *testing.T) {
	t.Helper()
	for _, k := range []string{
		"SMTP_HOST", "SMTP_PORT", "SMTP_PASSWORD",
		"SMTP_USERNAME", "SMTP_FROM", "SMTP_FROM_NAME",
		"SMTP_USER", "FROM_EMAIL", "FROM_NAME",
	} {
		t.Setenv(k, "")
	}
}

func TestLoadSMTPConfig_EmptyWhenNothingSet(t *testing.T) {
	clearAllSMTPEnv(t)
	cfg := LoadSMTPConfigFromEnv()
	assert.Empty(t, cfg.Host, "Host must stay empty so callers can log-only")
	assert.Empty(t, cfg.Port)
	assert.Empty(t, cfg.Username)
	assert.Empty(t, cfg.From)
	assert.Empty(t, cfg.FromName)
}

func TestLoadSMTPConfig_CanonicalNamesReadDirectly(t *testing.T) {
	clearAllSMTPEnv(t)
	t.Setenv("SMTP_HOST", "mailhog")
	t.Setenv("SMTP_PORT", "1025")
	t.Setenv("SMTP_USERNAME", "veza-api")
	t.Setenv("SMTP_PASSWORD", "supersecret")
	t.Setenv("SMTP_FROM", "no-reply@veza.fm")
	t.Setenv("SMTP_FROM_NAME", "Veza")

	cfg := LoadSMTPConfigFromEnv()
	assert.Equal(t, "mailhog", cfg.Host)
	assert.Equal(t, "1025", cfg.Port)
	assert.Equal(t, "veza-api", cfg.Username)
	assert.Equal(t, "supersecret", cfg.Password)
	assert.Equal(t, "no-reply@veza.fm", cfg.From)
	assert.Equal(t, "Veza", cfg.FromName)
}

func TestLoadSMTPConfig_DeprecatedNamesFallBack(t *testing.T) {
	clearAllSMTPEnv(t)
	// Only the pre-v1.0.6 env vars are set.
	t.Setenv("SMTP_USER", "legacy-user")
	t.Setenv("FROM_EMAIL", "legacy@veza.fm")
	t.Setenv("FROM_NAME", "Legacy Veza")

	core, observed := observer.New(zapcore.WarnLevel)
	cfg := LoadSMTPConfigFromEnvWithLogger(zap.New(core))

	assert.Equal(t, "legacy-user", cfg.Username, "fallback must pick up SMTP_USER when SMTP_USERNAME is empty")
	assert.Equal(t, "legacy@veza.fm", cfg.From)
	assert.Equal(t, "Legacy Veza", cfg.FromName)

	entries := observed.All()
	assert.Len(t, entries, 3, "one warning per deprecated var in use")
	seen := map[string]bool{}
	for _, e := range entries {
		for _, f := range e.Context {
			if f.Key == "deprecated" {
				seen[f.String] = true
			}
		}
	}
	assert.True(t, seen["SMTP_USER"])
	assert.True(t, seen["FROM_EMAIL"])
	assert.True(t, seen["FROM_NAME"])
}

func TestLoadSMTPConfig_CanonicalWinsOverDeprecated(t *testing.T) {
	clearAllSMTPEnv(t)
	t.Setenv("SMTP_USERNAME", "canonical-user")
	t.Setenv("SMTP_USER", "legacy-user-ignored")
	t.Setenv("SMTP_FROM", "canonical@veza.fm")
	t.Setenv("FROM_EMAIL", "legacy@veza.fm")

	core, observed := observer.New(zapcore.WarnLevel)
	cfg := LoadSMTPConfigFromEnvWithLogger(zap.New(core))
	assert.Equal(t, "canonical-user", cfg.Username)
	assert.Equal(t, "canonical@veza.fm", cfg.From)
	assert.Equal(t, 0, observed.Len(),
		"no warning should fire when canonical is set — deprecated vars are ignored silently")
}

func TestLoadSMTPConfig_NilLoggerIsAllowed(t *testing.T) {
	clearAllSMTPEnv(t)
	t.Setenv("SMTP_USER", "legacy")
	assert.NotPanics(t, func() { _ = LoadSMTPConfigFromEnv() })
	cfg := LoadSMTPConfigFromEnv()
	assert.Equal(t, "legacy", cfg.Username)
}