package setup

import (
	"html"
	"net/http"
	"net/url"

	"git.lohmar.co.uk/cclohmar/NextMyDay/internal/core/web"
)

// renderHTML writes the wizard page inside the core shell (SPEC-009 §4). The
// door renders no dynamic HTML itself (SPEC-003 §4); the wizard is the hand-off
// target for the `setup` workflow.
//
// F-2: the bootstrap renders secrets and ceremony state — never cache it.
func renderHTML(w http.ResponseWriter, status int, page web.Page) error {
	w.Header().Set("Cache-Control", "no-store")
	return web.Render(w, status, page)
}

// writeError writes a terse plain-text error.
func writeError(w http.ResponseWriter, status int, msg string) {
	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
	w.Header().Set("X-Content-Type-Options", "nosniff")
	w.WriteHeader(status)
	_, _ = w.Write([]byte(msg + "\n"))
}

// redirect sends the operator back to the wizard (post/redirect/get).
func redirect(w http.ResponseWriter, r *http.Request, path string) {
	http.Redirect(w, r, path, http.StatusSeeOther)
}

// wizardPage renders the current step inside the shell. The wizard runs before
// any identity exists, so the page is a GUEST screen: no nav (SPEC-009 §4).
// Every form carries the signed pre-session CSRF token (A15).
func wizardPage(st step, token, domain string) web.Page {
	c := html.EscapeString(token)
	return web.Page{
		Title: "MyDay setup",
		Guest: true,
		CSRF:  token,
		Content: web.Markup(`<h1>MyDay setup</h1>
<p>Bring this instance to life: the domain, the top admin, then mail and locale.</p>` +
			stepBody(st, c, domain)),
	}
}

// totpPage renders the wizard's TOTP step (SPEC-005 §4) once the secret has
// been issued: the otpauth URL, its human-readable secret for manual entry, and
// the verify form. The wizard is server-rendered and works with no JavaScript,
// so the secret is shown as text rather than encoded in a QR image; the page
// renders inside the shell (no inline scripts) and the verify form carries the
// signed pre-session CSRF token (A15).
func totpPage(token, otpauthURL string) web.Page {
	c := html.EscapeString(token)
	u := html.EscapeString(otpauthURL)
	secret := html.EscapeString(secretFromOtpauth(otpauthURL))
	return web.Page{
		Title: "MyDay setup",
		Guest: true,
		CSRF:  token,
		Content: web.Markup(`<h1>MyDay setup</h1>
<p>Add the authenticator, then enter a code from it to finish.</p>` +
			`<section aria-label="enroll"><h2>2. Enroll the admin</h2>` +
			`<p>A passkey can be added later, at first sign-in.</p>` +
			`<section aria-label="totp"><h3>Authenticator app</h3>` +
			`<p>Open this link in your authenticator app:</p>` +
			`<p><a href="` + u + `">` + u + `</a></p>` +
			`<p>Or enter this secret by hand:</p>` +
			`<p><code>` + secret + `</code></p>` +
			`<form method="post" action="/setup?do=setup&amp;action=admin.totp.verify">` +
			`<input type="hidden" name="csrf" value="` + c + `">` +
			`<label>Code <input name="code" inputmode="numeric" autocomplete="one-time-code"></label>` +
			`<button type="submit">Verify code</button></form></section></section>`),
	}
}

// secretFromOtpauth pulls the shared secret out of an otpauth:// URL for the
// manual-entry fallback. It returns "" when the URL carries none — the page then
// shows the link alone. The secret is never logged.
func secretFromOtpauth(raw string) string {
	u, err := url.Parse(raw)
	if err != nil {
		return ""
	}
	return u.Query().Get("secret")
}

// codeFormPage renders the D-044 first-run page — what `GET /setup` shows while
// `setup: true` and a required `setup_code` has not yet been entered. It is
// deliberately friendly: the point is that the domain must NOT look "down".
//
// It is a GUEST screen (no identity, no nav) with the setup-code entry form.
// The form submits over POST, so the code never rides the URL (and is never
// access-logged — the `code` parameter is redacted even if it ever did, A8).
func codeFormPage(token, flash string) web.Page {
	c := html.EscapeString(token)
	kind := ""
	if flash != "" {
		kind = "error"
	}
	return web.Page{
		Title:     "MyDay is not set up yet",
		Guest:     true,
		CSRF:      token,
		Flash:     flash,
		FlashKind: kind,
		Content: web.Markup(`<h1>MyDay is not set up yet</h1>
<p>This instance is waiting for its first-run setup. Open the setup wizard with the one-time
setup code that MyDay printed to its log when it started.</p>
<form method="post" action="/setup?do=setup&amp;action=unlock">
<input type="hidden" name="csrf" value="` + c + `">
<label>Setup code <input name="code" autocomplete="off" autocapitalize="off" spellcheck="false" autofocus required></label>
<button type="submit">Unlock setup</button>
</form>
<section aria-label="where to find the code">
<h2>Where is the code?</h2>
<p>It is in MyDay's startup log:</p>
<ul>
<li>in the container: <code>journalctl -u myday</code></li>
<li>from the Proxmox host: <code>pct exec 11020 -- journalctl -u myday</code></li>
</ul>
<p>Look for the line <code>setup code</code>.</p>
</section>`),
	}
}

// landingPage is the friendly page `GET /` shows while `setup: true` (D-045) —
// a pointer to the wizard. It carries no form and no code.
func landingPage() web.Page {
	return web.Page{
		Title: "MyDay setup",
		Guest: true,
		Content: web.Markup(`<h1>MyDay is ready for setup</h1>
<p>The setup wizard is enabled on this instance.</p>
<p><a href="/setup">Open the setup wizard</a></p>`),
	}
}

// lockedPage is what `GET /` and `GET /setup` show when `setup: false` and no
// admin exists yet (D-045): the instance is deliberately locked, not claimable.
// It is a GUEST screen with no form.
func lockedPage() web.Page {
	return web.Page{
		Title: "MyDay is not set up",
		Guest: true,
		Content: web.Markup(`<h1>MyDay is not set up</h1>
<p>This instance has no administrator yet, and setup is disabled.</p>
<p>To run the first-run setup, set <code>setup: true</code> in <code>config.yaml</code> and
restart MyDay. Then open <code>/setup</code>.</p>`),
	}
}

// stepBody renders the section for one step.
func stepBody(st step, c, domain string) string {
	switch st {
	case stepDomain:
		return `<section aria-label="domain"><h2>1. Domain</h2>` +
			`<form method="post" action="/setup?do=setup&amp;action=domain.save">` +
			`<input type="hidden" name="csrf" value="` + c + `">` +
			`<label>Base URL <input name="base_url" type="url" value="` +
			html.EscapeString(domain) + `" placeholder="https://myday.example.com" required></label>` +
			`<button type="submit">Continue</button></form></section>`

	case stepAdmin:
		return `<section aria-label="admin"><h2>2. The top admin</h2>` +
			`<form method="post" action="/setup?do=setup&amp;action=admin.create">` +
			`<input type="hidden" name="csrf" value="` + c + `">` +
			`<label>Display name <input name="display_name" autocomplete="name" required></label>` +
			`<label>Email <input name="email" type="email" autocomplete="email" required></label>` +
			`<button type="submit">Create the admin</button></form></section>`

	case stepEnroll:
		// Step 2 enrolls TOTP only (D-041): a passkey registered over loopback
		// would bind RP ID 127.0.0.1 and be dead at the public domain. The
		// admin adds a passkey at first login, via the nudge (SPEC-006 §8).
		return `<section aria-label="enroll"><h2>2. Enroll the admin</h2>` +
			`<p>Add an authenticator app. A passkey can be added later, at first sign-in.</p>` +
			`<section aria-label="totp"><h3>Authenticator app</h3>` +
			`<form method="post" action="/setup?do=setup&amp;action=admin.totp.begin">` +
			`<input type="hidden" name="csrf" value="` + c + `">` +
			`<button type="submit" class="secondary">Set up authenticator</button></form>` +
			`<form method="post" action="/setup?do=setup&amp;action=admin.totp.verify">` +
			`<input type="hidden" name="csrf" value="` + c + `">` +
			`<label>Code <input name="code" inputmode="numeric" autocomplete="one-time-code"></label>` +
			`<button type="submit">Verify code</button></form></section></section>`

	default: // stepSettings
		return `<section aria-label="settings"><h2>3. Mail · locale · timezone</h2>` +
			`<form method="post" action="/setup?do=setup&amp;action=finish">` +
			`<input type="hidden" name="csrf" value="` + c + `">` +
			`<label>SMTP host <input name="mail.host"></label>` +
			`<label>SMTP port <input name="mail.port" inputmode="numeric"></label>` +
			`<label>SMTP username <input name="mail.username"></label>` +
			`<label>SMTP password <input name="mail.password" type="password"></label>` +
			`<label>From address <input name="mail.from" type="email"></label>` +
			`<label>Locale <input name="app.locale" value="en-GB"></label>` +
			`<label>Timezone <input name="app.timezone" value="Europe/London"></label>` +
			`<button type="submit">Finish setup</button></form></section>`
	}
}