package mailfetch

import (
	"net/textproto"
	"strings"
	"testing"
)

// realForwardedHeaders mirrors the header set seen on a real forwarded message
// (AGENTS.md §13, message id 619). X-Pm-Original-To must win and Delivered-To
// must never be used.
func TestSourceAddressXPMOriginalToWins(t *testing.T) {
	h := textproto.MIMEHeader{}
	h.Set("X-Pm-Original-To", "Hello@where-woof.com")
	h.Set("To", "Hello@where-woof.com")
	h.Set("Return-Path", "<Hello@where-woof.com>")
	h.Set("Delivered-To", "samuelrolfe@gmail.com")

	addr, header := SourceAddress(h)
	if addr != "Hello@where-woof.com" {
		t.Errorf("address = %q, want %q", addr, "Hello@where-woof.com")
	}
	if header != "X-Pm-Original-To" {
		t.Errorf("header = %q, want %q", header, "X-Pm-Original-To")
	}
}

func TestSourceAddressFallsBackToTo(t *testing.T) {
	h := textproto.MIMEHeader{}
	h.Set("To", "Second Choice <second@example.test>")
	h.Set("Delivered-To", "samuelrolfe@gmail.com")

	addr, header := SourceAddress(h)
	if addr != "second@example.test" {
		t.Errorf("address = %q, want %q", addr, "second@example.test")
	}
	if header != "To" {
		t.Errorf("header = %q, want %q", header, "To")
	}
}

func TestSourceAddressFallsBackToReceivedFor(t *testing.T) {
	h := textproto.MIMEHeader{}
	h.Add("Received", "by mx.example.test with ESMTPS id abc")
	h.Add("Received", "from mail.purelymail.com by mx.example.test for <relay@where-woof.com>; Mon, 1 Jan 2026 00:00:00 +0000")
	h.Set("Return-Path", "<fallback@example.test>")

	addr, header := SourceAddress(h)
	if addr != "relay@where-woof.com" {
		t.Errorf("address = %q, want %q", addr, "relay@where-woof.com")
	}
	if header != "Received" {
		t.Errorf("header = %q, want %q", header, "Received")
	}
}

func TestSourceAddressFallsBackToReturnPath(t *testing.T) {
	h := textproto.MIMEHeader{}
	h.Set("Return-Path", "<sender@example.test>")

	addr, header := SourceAddress(h)
	if addr != "sender@example.test" {
		t.Errorf("address = %q, want %q", addr, "sender@example.test")
	}
	if header != "Return-Path" {
		t.Errorf("header = %q, want %q", header, "Return-Path")
	}
}

func TestSourceAddressIgnoresDeliveredTo(t *testing.T) {
	h := textproto.MIMEHeader{}
	h.Set("Delivered-To", "samuelrolfe@gmail.com")

	addr, header := SourceAddress(h)
	if addr != "" || header != "" {
		t.Errorf("SourceAddress() = (%q, %q), want empty: Delivered-To must not be used", addr, header)
	}
}

func TestParseMessagePlain(t *testing.T) {
	raw := strings.Join([]string{
		"From: favrolfe@gmail.com",
		"To: Hello@where-woof.com",
		"X-Pm-Original-To: Hello@where-woof.com",
		"Subject: =?UTF-8?Q?Caf=C3=A9_meeting?=",
		"Date: Mon, 02 Oct 2006 15:04:05 -0700",
		"Content-Type: text/plain; charset=utf-8",
		"Content-Transfer-Encoding: quoted-printable",
		"",
		"Hello there=2C this is a test.",
	}, "\r\n")

	pm, err := ParseMessage([]byte(raw))
	if err != nil {
		t.Fatalf("ParseMessage() error = %v", err)
	}
	if pm.Subject != "Café meeting" {
		t.Errorf("Subject = %q, want %q", pm.Subject, "Café meeting")
	}
	if pm.SourceAddress != "Hello@where-woof.com" || pm.SourceHeader != "X-Pm-Original-To" {
		t.Errorf("source = (%q, %q), want (Hello@where-woof.com, X-Pm-Original-To)", pm.SourceAddress, pm.SourceHeader)
	}
	if !strings.Contains(pm.BodyText, "Hello there, this is a test.") {
		t.Errorf("BodyText = %q, want quoted-printable decoded text", pm.BodyText)
	}
}

func TestParseMessageMultipartPrefersPlain(t *testing.T) {
	raw := strings.Join([]string{
		"From: sender@example.test",
		"To: Hello@where-woof.com",
		"Subject: multipart",
		"MIME-Version: 1.0",
		`Content-Type: multipart/alternative; boundary="BOUND"`,
		"",
		"--BOUND",
		"Content-Type: text/plain; charset=utf-8",
		"",
		"plain part wins",
		"--BOUND",
		"Content-Type: text/html; charset=utf-8",
		"",
		"<p>html part <b>loses</b></p>",
		"--BOUND--",
		"",
	}, "\r\n")

	pm, err := ParseMessage([]byte(raw))
	if err != nil {
		t.Fatalf("ParseMessage() error = %v", err)
	}
	if !strings.Contains(pm.BodyText, "plain part wins") {
		t.Errorf("BodyText = %q, want the text/plain part", pm.BodyText)
	}
	if strings.Contains(pm.BodyText, "html part") {
		t.Errorf("BodyText = %q, must not contain the HTML part", pm.BodyText)
	}
}

func TestParseMessageHTMLOnlyIsStripped(t *testing.T) {
	raw := strings.Join([]string{
		"From: sender@example.test",
		"Subject: html only",
		"Content-Type: text/html; charset=utf-8",
		"",
		"<html><body><h1>Hello</h1><p>World&nbsp;&amp; friends</p></body></html>",
	}, "\r\n")

	pm, err := ParseMessage([]byte(raw))
	if err != nil {
		t.Fatalf("ParseMessage() error = %v", err)
	}
	if !strings.Contains(pm.BodyText, "Hello") || !strings.Contains(pm.BodyText, "World & friends") {
		t.Errorf("BodyText = %q, want stripped HTML text", pm.BodyText)
	}
	if strings.Contains(pm.BodyText, "<") {
		t.Errorf("BodyText = %q, want no tags", pm.BodyText)
	}
}

func TestHeaderAddressParsing(t *testing.T) {
	cases := []struct{ in, want string }{
		{"Hello@where-woof.com", "Hello@where-woof.com"},
		{"<Hello@where-woof.com>", "Hello@where-woof.com"},
		{"Sam Rolfe <sam@example.test>", "sam@example.test"},
		{"a@example.test, b@example.test", "a@example.test"},
		{"", ""},
	}
	for _, tc := range cases {
		if got := headerAddress(tc.in); got != tc.want {
			t.Errorf("headerAddress(%q) = %q, want %q", tc.in, got, tc.want)
		}
	}
}