package templates

import (
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"testing"
)

// CSP tripwire.
//
// script-src is hash-allow-listed (no 'unsafe-inline' — see
// internal/middleware/security_headers.go). That makes the browser refuse,
// silently at build time, two authoring patterns:
//
//  1. Inline <script> content whose bytes are not in the allow-list. The
//     theme flash guard is the ONLY inline script in the app; its hash is
//     pinned (and drift-checked) by middleware's
//     TestThemeFlashGuardHashMatchesCSP. A second inline script renders
//     fine and simply never executes.
//  2. Native on*= event-handler attributes (onclick=, onchange=, ...).
//     Inline handlers never go through the hash path at all — they are
//     always refused under hash-mode CSP. Alpine @click/@change component
//     methods are the replacement (see the 2026-10 conversion commits).
//
// Neither failure mode is observable in Go tests or at build time, so this
// source scan IS the tripwire: it fails the build if either pattern appears
// in a templ source file. htmx's eval-dependent bindings (hx-on*, js:-
// prefixed hx-vals) are included — 'unsafe-eval' is not granted either.

var cspHandlerAttrRe = regexp.MustCompile(
	`on(click|error|submit|load|change|input|focus|blur|mouseover|keydown|keyup)\s*=\s*("|\{)`)

var cspInlineScriptRe = regexp.MustCompile(`(?s)<script\b([^>]*)>`)

var cspEvalBindingRe = regexp.MustCompile(
	`\b(hx-on[a-z:-]*|data-hx-on[a-z:-]*)\s*=|(hx-vals|data-hx-vals)\s*=\s*["'][^"']*\bjs:`)

// cspSanctionedInlineScripts lists the templ files allowed to carry inline
// <script> content. The theme flash guard's bytes are pinned by the CSP
// hash + drift test in internal/middleware.
var cspSanctionedInlineScripts = map[string]bool{
	"theme_flash_guard.templ": true,
}

func TestTemplSourcesAreCSPSafe(t *testing.T) {
	files, err := filepath.Glob("*.templ")
	if err != nil {
		t.Fatal(err)
	}
	if len(files) == 0 {
		t.Fatal("no .templ files found — this test must run from the templates package directory")
	}

	for _, f := range files {
		raw, err := os.ReadFile(f)
		if err != nil {
			t.Fatal(err)
		}
		src := string(raw)

		for _, m := range cspHandlerAttrRe.FindAllStringIndex(src, -1) {
			t.Errorf("%s:%d: native on*= handler attribute (%s) — CSP hash-mode refuses it; use an Alpine @binding with a component method",
				f, 1+strings.Count(src[:m[0]], "\n"), src[m[0]:m[1]])
		}

		for _, m := range cspInlineScriptRe.FindAllStringSubmatchIndex(src, -1) {
			tag := src[m[0]:m[1]]
			if strings.Contains(tag, "src=") {
				continue // external script, governed by script-src 'self'
			}
			if cspSanctionedInlineScripts[filepath.Base(f)] {
				continue // the theme flash guard: hash-pinned in middleware
			}
			t.Errorf("%s:%d: inline <script> without src= (%s) — only the theme flash guard may be inline; add its hash to middleware.ScriptHashThemeFlashGuard + the drift test, or move the code to a bundled module",
				f, 1+strings.Count(src[:m[0]], "\n"), tag)
		}

		for _, m := range cspEvalBindingRe.FindAllStringIndex(src, -1) {
			t.Errorf("%s:%d: htmx eval-dependent binding (%s) — 'unsafe-eval' is not granted; use hx-trigger/hx-post forms that need no eval",
				f, 1+strings.Count(src[:m[0]], "\n"), src[m[0]:m[1]])
		}
	}
}