package notify

import (
	"context"
	"encoding/json"
	"fmt"
	"net"
	"net/http"
	"strings"
	"testing"
	"time"

	"rocketgit.ru/rsmon/worker/app/models"
)

const (
	mailhogSMTPHost     = "localhost"
	mailhogSMTPPort     = 31025
	mailhogAPIURL       = "http://localhost:38025"
	networkDialTimeout  = 2 * time.Second
	mailhogPollInterval = 100 * time.Millisecond
	mailhogPollDeadline = 3 * time.Second
)

// mailhogMessage mirrors the subset of MailHog's /api/v2/messages payload we
// care about in tests: the parsed headers and the rendered body.
type mailhogMessage struct {
	Content struct {
		Headers map[string][]string `json:"Headers"`
		Body    string              `json:"Body"`
	} `json:"Content"`
}

// skipIfMailHogDown skips the test if MailHog's SMTP port is unreachable.
// Tests stay green on dev machines without docker; on CI with docker they
// run for real against the running MailHog container.
func skipIfMailHogDown(t *testing.T) {
	t.Helper()
	addr := net.JoinHostPort(mailhogSMTPHost, fmt.Sprintf("%d", mailhogSMTPPort))
	conn, err := net.DialTimeout("tcp", addr, networkDialTimeout)
	if err != nil {
		t.Skipf("mailhog not reachable at %s: %v", addr, err)
	}
	_ = conn.Close()
}

// mailhogMessages fetches the most recent messages from MailHog's HTTP API.
func mailhogMessages(t *testing.T) []mailhogMessage {
	t.Helper()
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, mailhogAPIURL+"/api/v2/messages?limit=50", nil)
	if err != nil {
		t.Fatalf("build mailhog request: %v", err)
	}
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("query mailhog: %v", err)
	}
	defer func() { _ = resp.Body.Close() }()

	var out struct {
		Total int              `json:"total"`
		Items []mailhogMessage `json:"items"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&out); err != nil {
		t.Fatalf("decode mailhog response: %v", err)
	}
	return out.Items
}

// mailhogDeleteAll clears the MailHog in-memory mailbox so each test starts
// from a known state.
func mailhogDeleteAll(t *testing.T) {
	t.Helper()
	req, err := http.NewRequest(http.MethodDelete, mailhogAPIURL+"/api/v1/messages", nil)
	if err != nil {
		t.Fatalf("build mailhog delete: %v", err)
	}
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("delete mailhog messages: %v", err)
	}
	defer func() { _ = resp.Body.Close() }()
	if resp.StatusCode != http.StatusOK {
		t.Fatalf("mailhog delete returned %d", resp.StatusCode)
	}
}

func TestEmail_Network_SendAndVerify(t *testing.T) {
	skipIfMailHogDown(t)
	mailhogDeleteAll(t)

	port := mailhogSMTPPort
	enabled := true
	cred := &models.NotificationCredential{
		Kind:     models.CredentialKindSMTP,
		Name:     "mailhog-test",
		Server:   strPtr(mailhogSMTPHost),
		Port:     &port,
		Login:    strPtr(""),
		FromName: strPtr("RSMon Tests"),
		FromAddr: strPtr("tests@rsmon.test"),
		Enabled:  &enabled,
		// MailHog accepts any password; "plain:" prefix keeps GetSecret
		// working without the credential encryption key configured.
		SecretEnc: "plain:",
	}

	subject := "rsmon-test-subject-" + time.Now().Format("150405.000")
	body := "rsmon-test-body hello mailhog"
	to := "to@rsmon.test"

	if err := Email(cred, to, subject, body, ""); err != nil {
		t.Fatalf("Email returned error: %v", err)
	}

	deadline := time.Now().Add(mailhogPollDeadline)
	var found *mailhogMessage
	for time.Now().Before(deadline) {
		msgs := mailhogMessages(t)
		for i := range msgs {
			hsubj := msgs[i].Content.Headers["Subject"]
			if len(hsubj) > 0 && strings.Contains(hsubj[0], subject) {
				found = &msgs[i]
				break
			}
		}
		if found != nil {
			break
		}
		time.Sleep(mailhogPollInterval)
	}
	if found == nil {
		t.Fatalf("message with subject %q not found in MailHog after %s", subject, mailhogPollDeadline)
	}

	if !strings.Contains(found.Content.Body, body) {
		t.Errorf("body mismatch: want contains %q, got %q", body, found.Content.Body)
	}
	if hfrom := found.Content.Headers["From"]; len(hfrom) == 0 || !strings.Contains(hfrom[0], "tests@rsmon.test") {
		t.Errorf("from mismatch: want contains tests@rsmon.test, got %v", hfrom)
	}
	if hto := found.Content.Headers["To"]; len(hto) == 0 || !strings.Contains(hto[0], to) {
		t.Errorf("to mismatch: want contains %s, got %v", to, hto)
	}
}

func TestEmail_Network_HTMLAlternative(t *testing.T) {
	skipIfMailHogDown(t)
	mailhogDeleteAll(t)

	port := mailhogSMTPPort
	enabled := true
	cred := &models.NotificationCredential{
		Kind:      models.CredentialKindSMTP,
		Name:      "mailhog-html",
		Server:    strPtr(mailhogSMTPHost),
		Port:      &port,
		Login:     strPtr(""),
		FromAddr:  strPtr("tests@rsmon.test"),
		Enabled:   &enabled,
		SecretEnc: "plain:",
	}

	subject := "rsmon-html-" + time.Now().Format("150405.000")
	bodyText := "plain text body"
	bodyHTML := "<p>html <b>body</b></p>"

	if err := Email(cred, "to@rsmon.test", subject, bodyText, bodyHTML); err != nil {
		t.Fatalf("Email returned error: %v", err)
	}

	deadline := time.Now().Add(mailhogPollDeadline)
	var found *mailhogMessage
	for time.Now().Before(deadline) {
		msgs := mailhogMessages(t)
		for i := range msgs {
			hsubj := msgs[i].Content.Headers["Subject"]
			if len(hsubj) > 0 && strings.Contains(hsubj[0], subject) {
				found = &msgs[i]
				break
			}
		}
		if found != nil {
			break
		}
		time.Sleep(mailhogPollInterval)
	}
	if found == nil {
		t.Fatalf("html message with subject %q not found in MailHog after %s", subject, mailhogPollDeadline)
	}

	body := found.Content.Body
	if !strings.Contains(body, bodyText) {
		t.Errorf("text part missing: want contains %q in %q", bodyText, body)
	}
	if !strings.Contains(body, bodyHTML) {
		t.Errorf("html part missing: want contains %q in %q", bodyHTML, body)
	}
}