// This file is part of the happyDomain (R) project.
// Copyright (c) 2020-2026 happyDomain
// Authors: Pierre-Olivier Mercier, et al.
//
// This program is offered under a commercial and under the AGPL license.
// For commercial licensing, contact us at <contact@happydomain.org>.

// Package checker implements an HTTP/HTTPS server checker for happyDomain.
// It probes the abstract.Server it is attached to over HTTP (80) and HTTPS
// (443), captures response headers, cookies and the (parsed) HTML body, then
// evaluates a set of independent rules covering reachability, the HTTP→HTTPS
// upgrade path, modern transport-security headers (HSTS, CSP), application
// security headers (X-Frame-Options, X-Content-Type-Options, X-XSS-Protection)
// and Subresource Integrity. Deep TLS / certificate analysis is intentionally
// delegated to checker-tls.
package checker

import (
	"encoding/json"
	"time"
)

const ObservationKeyHTTP = "http"

const (
	OptionService           = "service"
	OptionDomainName        = "domain_name"
	OptionProbeTimeoutMs    = "probeTimeoutMs"
	OptionMaxRedirects      = "maxRedirects"
	OptionUserAgent         = "userAgent"
	OptionRequireHTTPS      = "requireHTTPS"
	OptionRequireHSTS       = "requireHSTS"
	OptionMinHSTSMaxAgeDays = "minHSTSMaxAgeDays"
	OptionRequireCSP        = "requireCSP"
)

const (
	DefaultHTTPPort       uint16 = 80
	DefaultHTTPSPort      uint16 = 443
	DefaultProbeTimeoutMs = 10000
	DefaultMaxRedirects   = 5
	DefaultUserAgent      = "happyDomain-checker-http/1.0"
	DefaultMinHSTSMaxAge  = 180 // days; 180d ≈ 15552000s, the commonly recommended minimum
	MaxConcurrentProbes   = 8
	MaxBodyBytes          = 1 << 20 // 1 MiB cap on HTML body to keep memory bounded
)

// HTTPData is the full collected payload written under ObservationKeyHTTP.
//
// Probes/Domain/CollectedAt come from the root collector and are kept at
// the top level for backward compatibility with the rules that have
// always read them directly.
//
// Extensions holds the JSON-encoded outputs of every additional Collector
// registered via RegisterCollector, keyed by Collector.Key(). Rules
// access them via LoadExtension[T] to get a typed view.
type HTTPData struct {
	Domain      string      `json:"domain,omitempty"`
	Probes      []HTTPProbe `json:"probes"`
	CollectedAt time.Time   `json:"collected_at"`

	Extensions map[string]json.RawMessage `json:"extensions,omitempty"`
}

// HTTPProbe is the outcome of a single (scheme, ip, port) probe.
type HTTPProbe struct {
	Scheme  string `json:"scheme"` // "http" or "https"
	Host    string `json:"host"`
	IP      string `json:"ip,omitempty"`
	Port    uint16 `json:"port"`
	Address string `json:"address"`
	IsIPv6  bool   `json:"ipv6,omitempty"`

	TCPConnected bool   `json:"tcp_connected"`
	ElapsedMS    int64  `json:"elapsed_ms,omitempty"`
	Error        string `json:"error,omitempty"`

	// Final response after following redirects (if any).
	StatusCode    int               `json:"status_code,omitempty"`
	FinalURL      string            `json:"final_url,omitempty"`
	Headers       map[string]string `json:"headers,omitempty"`
	Cookies       []CookieInfo      `json:"cookies,omitempty"`
	RedirectChain []RedirectStep    `json:"redirect_chain,omitempty"`

	// Parsed HTML resource references (only populated for the primary
	// HTTPS probe, to keep payloads small).
	Resources     []HTMLResource `json:"resources,omitempty"`
	HTMLBytes     int            `json:"html_bytes,omitempty"`
	BodyTruncated bool           `json:"body_truncated,omitempty"`
}

// RedirectStep records one hop of a redirect chain.
type RedirectStep struct {
	From   string `json:"from"`
	To     string `json:"to"`
	Status int    `json:"status"`
}

// CookieInfo summarises one Set-Cookie header.
type CookieInfo struct {
	Name      string `json:"name"`
	Domain    string `json:"domain,omitempty"`
	Path      string `json:"path,omitempty"`
	Secure    bool   `json:"secure"`
	HttpOnly  bool   `json:"http_only"`
	SameSite  string `json:"same_site,omitempty"` // "Strict", "Lax", "None", or ""
	HasExpiry bool   `json:"has_expiry,omitempty"`
	// Size is the byte length of the raw Set-Cookie header value
	// (everything after "Set-Cookie: "), used to evaluate the
	// per-cookie 4096-byte budget RFC 6265 §6.1 says browsers SHOULD
	// support.
	Size int `json:"size,omitempty"`
}

// MaxCookieSize is the per-cookie size browsers are required to
// support per RFC 6265 §6.1. Cookies above this are likely to be
// silently dropped by some user agents.
const MaxCookieSize = 4096

// HTMLResource is a <script src=...> or <link href=...> reference extracted
// from the HTML body, used to evaluate Subresource Integrity coverage.
type HTMLResource struct {
	Tag         string `json:"tag"` // "script" or "link"
	URL         string `json:"url"`
	CrossOrigin bool   `json:"cross_origin"`
	Integrity   string `json:"integrity,omitempty"`
	Rel         string `json:"rel,omitempty"`
}

// Severity levels used internally by rules.
const (
	SeverityCrit = "crit"
	SeverityWarn = "warn"
	SeverityInfo = "info"
	SeverityOK   = "ok"
)