httpcan 0.8.1

use super::*;
use std::fmt::Write as _;

/// Compatibility status relative to the original httpbin.org (see
/// `https://httpbin.org/spec.json`), rendered as a small badge next to each
/// endpoint on the homepage. Endpoints with no badge behave the same as
/// httpbin and are drop-in compatible.
#[derive(Clone, Copy, PartialEq, Eq)]
enum Badge {
    /// httpbin has this endpoint; httpcan fixes a bug or adds a capability.
    Enhanced,
    /// Not available in httpbin.org at all.
    New,
}

impl Badge {
    fn label(self) -> &'static str {
        match self {
            Badge::Enhanced => "Enhanced",
            Badge::New => "New",
        }
    }

    fn css_class(self) -> &'static str {
        match self {
            Badge::Enhanced => "badge badge-enhanced",
            Badge::New => "badge badge-new",
        }
    }

    fn title(self) -> &'static str {
        match self {
            Badge::Enhanced => {
                "httpbin.org has this endpoint; httpcan fixes a bug or adds a capability"
            }
            Badge::New => "Not available in httpbin.org",
        }
    }
}

struct Endpoint {
    methods: &'static str,
    path: &'static str,
    badge: Option<Badge>,
    desc: &'static str,
    /// Example curl invocation, with path/query params already filled in
    /// with realistic sample values. `{base}` is substituted with the
    /// current request's origin (e.g. `http://localhost:8080`) at render
    /// time, so the copied command actually works against this instance.
    curl: &'static str,
}

struct Category {
    id: &'static str,
    title: &'static str,
    desc: &'static str,
    endpoints: &'static [Endpoint],
}

const CATEGORIES: &[Category] = &[
    Category {
        id: "http-methods",
        title: "HTTP Methods",
        desc: "Testing different HTTP verbs.",
        endpoints: &[
            Endpoint { methods: "GET", path: "/get", badge: None, desc: "Echoes the request's query parameters, headers, origin, and URL (GET and HEAD).", curl: "curl '{base}/get?greeting=hello'" },
            Endpoint { methods: "POST", path: "/post", badge: Some(Badge::Enhanced), desc: "Echoes the request's parsed body and uploaded files; same-named multipart fields collect into an array.", curl: "curl -X POST {base}/post -H 'Content-Type: application/json' -d '{\"key\":\"value\"}'" },
            Endpoint { methods: "PUT", path: "/put", badge: Some(Badge::Enhanced), desc: "Same as /post, for PUT requests.", curl: "curl -X PUT {base}/put -H 'Content-Type: application/json' -d '{\"key\":\"value\"}'" },
            Endpoint { methods: "PATCH", path: "/patch", badge: Some(Badge::Enhanced), desc: "Same as /post, for PATCH requests.", curl: "curl -X PATCH {base}/patch -H 'Content-Type: application/json' -d '{\"key\":\"value\"}'" },
            Endpoint { methods: "DELETE", path: "/delete", badge: None, desc: "Same as /post, for DELETE requests.", curl: "curl -X DELETE {base}/delete" },
            Endpoint { methods: "HEAD", path: "/head", badge: Some(Badge::New), desc: "HEAD-only: echoes the request headers back as X-Echo-* response headers.", curl: "curl -I {base}/head" },
            Endpoint { methods: "OPTIONS", path: "/options", badge: Some(Badge::New), desc: "OPTIONS-only: echoes the request and returns an Allow header (RFC 9110 §9.3.7).", curl: "curl -X OPTIONS {base}/options" },
            Endpoint { methods: "TRACE", path: "/trace", badge: Some(Badge::New), desc: "TRACE-only: echoes the request like /anything (RFC 9110 §9.8).", curl: "curl -X TRACE {base}/trace" },
            Endpoint { methods: "QUERY", path: "/query", badge: Some(Badge::New), desc: "Echoes the request's URL args and parsed body, like /post (RFC 9430).", curl: "curl -X QUERY {base}/query -d 'select=everything'" },
        ],
    },
    Category {
        id: "anything",
        title: "Anything",
        desc: "Returns anything that is passed to the request.",
        endpoints: &[
            Endpoint { methods: "GET/POST/PUT/PATCH/DELETE/OPTIONS/TRACE/QUERY", path: "/anything", badge: Some(Badge::Enhanced), desc: "Accepts any method and echoes the full request; multipart handling matches /post.", curl: "curl -X POST {base}/anything -d 'hello httpcan'" },
            Endpoint { methods: "GET/POST/PUT/PATCH/DELETE/OPTIONS/TRACE/QUERY", path: "/anything/{path}", badge: Some(Badge::Enhanced), desc: "Same as /anything, with extra path segment(s) that are ignored.", curl: "curl {base}/anything/foo/bar" },
        ],
    },
    Category {
        id: "auth",
        title: "Auth",
        desc: "Auth methods.",
        endpoints: &[
            Endpoint { methods: "GET/POST", path: "/basic-auth/{user}/{passwd}", badge: None, desc: "Challenges HTTP Basic Auth with the given credentials.", curl: "curl -u user:pass {base}/basic-auth/user/pass" },
            Endpoint { methods: "GET/POST", path: "/basic-auth/{user}", badge: Some(Badge::New), desc: "Challenges HTTP Basic Auth with an empty password (username-only check).", curl: "curl -u 'user:' {base}/basic-auth/user" },
            Endpoint { methods: "GET/POST", path: "/hidden-basic-auth/{user}/{passwd}", badge: None, desc: "Like /basic-auth, but returns 404 instead of 401 on failure.", curl: "curl -u user:pass {base}/hidden-basic-auth/user/pass" },
            Endpoint { methods: "GET/POST", path: "/hidden-basic-auth/{user}", badge: Some(Badge::New), desc: "Like /basic-auth/{user}, but returns 404 instead of 401 on failure.", curl: "curl -u 'user:' {base}/hidden-basic-auth/user" },
            Endpoint { methods: "GET", path: "/bearer", badge: None, desc: "Checks for a Bearer token in the Authorization header.", curl: "curl -H 'Authorization: Bearer mytoken123' {base}/bearer" },
            Endpoint { methods: "GET", path: "/jwt-bearer", badge: Some(Badge::New), desc: "Decodes and inspects a JWT Bearer token, without verifying its signature.", curl: "curl -H 'Authorization: Bearer eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiIxMjM0NTY3ODkwIn0.sflKxw' {base}/jwt-bearer" },
            Endpoint { methods: "GET/POST", path: "/digest-auth/{qop}/{user}/{passwd}[/{algorithm}[/{stale_after}]]", badge: Some(Badge::Enhanced), desc: "Challenges HTTP Digest Auth; adds SHA-512-256 and a qop=none legacy (RFC 2069) mode.", curl: "curl --digest -u user:pass {base}/digest-auth/auth/user/pass" },
        ],
    },
    Category {
        id: "status-codes",
        title: "Status codes",
        desc: "Generates responses with a given status code.",
        endpoints: &[
            Endpoint { methods: "GET/POST/PUT/PATCH/DELETE/TRACE/OPTIONS", path: "/status/{codes}", badge: Some(Badge::Enhanced), desc: "Returns the given status, or a random one from a comma-separated list; supports ?header= injection, a custom body, and trailing path segments.", curl: "curl -i '{base}/status/429?header=Retry-After:120'" },
        ],
    },
    Category {
        id: "request-inspection",
        title: "Request inspection",
        desc: "Inspect the request data.",
        endpoints: &[
            Endpoint { methods: "GET", path: "/headers", badge: None, desc: "Returns the request's HTTP headers.", curl: "curl {base}/headers" },
            Endpoint { methods: "GET", path: "/ip", badge: None, desc: "Returns the requester's IP address.", curl: "curl {base}/ip" },
            Endpoint { methods: "GET", path: "/user-agent", badge: None, desc: "Returns the request's User-Agent header.", curl: "curl {base}/user-agent" },
            Endpoint { methods: "ANY", path: "/method", badge: Some(Badge::New), desc: "Returns the request's HTTP method name.", curl: "curl -X LINK {base}/method" },
            Endpoint { methods: "GET/POST/PUT/PATCH/DELETE/QUERY", path: "/body", badge: Some(Badge::New), desc: "Returns the request's body verbatim with mirrored headers, for any method including QUERY (RFC 9430); /echo is a compatibility alias.", curl: "curl -X POST {base}/body -d 'hello httpcan'" },
        ],
    },
    Category {
        id: "response-inspection",
        title: "Response inspection",
        desc: "Inspect the response data, like caching and headers.",
        endpoints: &[
            Endpoint { methods: "GET", path: "/cache", badge: None, desc: "Returns 304 if If-Modified-Since or If-None-Match is present, 200 otherwise.", curl: "curl -i -H 'If-None-Match: \"abc123\"' {base}/cache" },
            Endpoint { methods: "GET", path: "/cache/{value}", badge: None, desc: "Sets a Cache-Control header for the given number of seconds.", curl: "curl -i {base}/cache/60" },
            Endpoint { methods: "GET", path: "/etag/{etag}", badge: Some(Badge::Enhanced), desc: "Validates If-Match/If-None-Match against the given ETag; supports weak W/\"...\" validators.", curl: "curl -i -H 'If-None-Match: \"abc123\"' {base}/etag/abc123" },
            Endpoint { methods: "GET/POST", path: "/response-headers", badge: Some(Badge::Enhanced), desc: "Echoes query parameters as response headers; ?body= and ?status= override the response body and status code.", curl: "curl -i '{base}/response-headers?Content-Type=text/plain&X-Foo=bar'" },
        ],
    },
    Category {
        id: "response-formats",
        title: "Response formats",
        desc: "Returns responses in different data formats.",
        endpoints: &[
            Endpoint { methods: "GET", path: "/json", badge: None, desc: "Returns a sample JSON document.", curl: "curl {base}/json" },
            Endpoint { methods: "GET", path: "/xml", badge: None, desc: "Returns a sample XML document.", curl: "curl {base}/xml" },
            Endpoint { methods: "GET", path: "/html", badge: None, desc: "Returns a sample HTML document.", curl: "curl {base}/html" },
            Endpoint { methods: "GET", path: "/deny", badge: None, desc: "Returns the page that robots.txt disallows.", curl: "curl {base}/deny" },
            Endpoint { methods: "GET", path: "/encoding/utf8", badge: None, desc: "Returns a UTF-8 encoded page.", curl: "curl {base}/encoding/utf8" },
            Endpoint { methods: "GET", path: "/encoding/iso-8859-1", badge: Some(Badge::New), desc: "Returns an ISO-8859-1 encoded page.", curl: "curl {base}/encoding/iso-8859-1" },
            Endpoint { methods: "GET/POST", path: "/gzip", badge: Some(Badge::Enhanced), desc: "GET returns gzip-encoded JSON; POST gzip-encodes the request body.", curl: "curl {base}/gzip | gunzip" },
            Endpoint { methods: "GET/POST", path: "/deflate", badge: Some(Badge::Enhanced), desc: "GET returns deflate-encoded JSON; POST deflate-encodes the request body.", curl: "curl {base}/deflate" },
            Endpoint { methods: "GET/POST", path: "/brotli", badge: Some(Badge::Enhanced), desc: "GET returns brotli-encoded JSON; POST brotli-encodes the request body.", curl: "curl {base}/brotli" },
            Endpoint { methods: "GET/POST", path: "/zstd", badge: Some(Badge::New), desc: "GET returns Zstandard-encoded JSON; POST zstd-encodes the request body.", curl: "curl {base}/zstd" },
        ],
    },
    Category {
        id: "dynamic-data",
        title: "Dynamic data",
        desc: "Generates random and dynamic data.",
        endpoints: &[
            Endpoint { methods: "GET", path: "/uuid", badge: None, desc: "Returns a UUIDv4.", curl: "curl {base}/uuid" },
            Endpoint { methods: "GET", path: "/base64/{value}", badge: Some(Badge::Enhanced), desc: "Decodes a standard base64 string; returns raw bytes for non-UTF-8 content instead of erroring.", curl: "curl {base}/base64/SFRUUENhbiBpcyBhd2Vzb21l" },
            Endpoint { methods: "POST", path: "/base64", badge: Some(Badge::New), desc: "Decodes the request body as base64.", curl: "curl -X POST {base}/base64 -d 'SFRUUENhbiBpcyBhd2Vzb21l'" },
            Endpoint { methods: "GET", path: "/bytes/{n}", badge: Some(Badge::Enhanced), desc: "Returns n random bytes; over the configured --max-bytes limit returns 404 instead of silently truncating.", curl: "curl {base}/bytes/1024 -o random.bin" },
            Endpoint { methods: "GET", path: "/stream-bytes/{n}", badge: Some(Badge::Enhanced), desc: "Streams n random bytes chunk by chunk; same limit behavior as /bytes.", curl: "curl {base}/stream-bytes/1024 -o random.bin" },
            Endpoint { methods: "GET", path: "/stream/{n}", badge: None, desc: "Streams n JSON lines describing the request.", curl: "curl -N {base}/stream/5" },
            Endpoint { methods: "GET", path: "/range/{numbytes}", badge: None, desc: "Streams numbytes bytes; supports Range requests.", curl: "curl -H 'Range: bytes=0-99' {base}/range/1024" },
            Endpoint { methods: "GET", path: "/links/{n}/{offset}", badge: None, desc: "Returns a page of n links, starting at offset.", curl: "curl {base}/links/5/0" },
            Endpoint { methods: "GET", path: "/links/{n}", badge: Some(Badge::New), desc: "Same as /links/{n}/{offset}, with offset defaulted to 0.", curl: "curl {base}/links/5" },
            Endpoint { methods: "GET", path: "/drip", badge: Some(Badge::Enhanced), desc: "Drips data over a duration; ?chunked=true streams with real chunked transfer-encoding.", curl: "curl '{base}/drip?duration=2&numbytes=10&delay=1&chunked=true'" },
            Endpoint { methods: "GET/POST/PUT/PATCH/DELETE/TRACE", path: "/delay/{delay}", badge: None, desc: "Delays the response by up to 10 seconds.", curl: "curl {base}/delay/3" },
        ],
    },
    Category {
        id: "cookies",
        title: "Cookies",
        desc: "Creates, reads, and deletes cookies.",
        endpoints: &[
            Endpoint { methods: "GET", path: "/cookies", badge: None, desc: "Returns the request's cookies.", curl: "curl -b 'session=abc123' {base}/cookies" },
            Endpoint { methods: "GET", path: "/cookies/set", badge: Some(Badge::Enhanced), desc: "Sets cookies from query parameters and redirects to /cookies; supports httponly/secure/samesite/domain/path/max_age attributes.", curl: "curl -i '{base}/cookies/set?session=abc123&httponly=true&samesite=lax'" },
            Endpoint { methods: "GET", path: "/cookies/set/{name}/{value}", badge: None, desc: "Sets a single cookie and redirects to /cookies.", curl: "curl -i {base}/cookies/set/session/abc123" },
            Endpoint { methods: "GET", path: "/cookies/delete", badge: None, desc: "Deletes the given cookies and redirects to /cookies.", curl: "curl -i '{base}/cookies/delete?session'" },
        ],
    },
    Category {
        id: "images",
        title: "Images",
        desc: "Returns different image formats.",
        endpoints: &[
            Endpoint { methods: "GET", path: "/image", badge: None, desc: "Returns a random image; format negotiated via the Accept header.", curl: "curl -H 'Accept: image/webp' {base}/image -o image.webp" },
            Endpoint { methods: "GET", path: "/image/png", badge: None, desc: "Returns a PNG image.", curl: "curl {base}/image/png -o image.png" },
            Endpoint { methods: "GET", path: "/image/jpeg", badge: None, desc: "Returns a JPEG image.", curl: "curl {base}/image/jpeg -o image.jpg" },
            Endpoint { methods: "GET", path: "/image/webp", badge: None, desc: "Returns a WEBP image.", curl: "curl {base}/image/webp -o image.webp" },
            Endpoint { methods: "GET", path: "/image/svg", badge: None, desc: "Returns an SVG image.", curl: "curl {base}/image/svg -o image.svg" },
        ],
    },
    Category {
        id: "redirects",
        title: "Redirects",
        desc: "Returns different redirect responses.",
        endpoints: &[
            Endpoint { methods: "GET", path: "/redirect/{n}", badge: None, desc: "Redirects n times before returning 200.", curl: "curl -L {base}/redirect/3" },
            Endpoint { methods: "GET", path: "/relative-redirect/{n}", badge: None, desc: "Same as /redirect/{n}, using relative Location URLs.", curl: "curl -L {base}/relative-redirect/3" },
            Endpoint { methods: "GET", path: "/absolute-redirect/{n}", badge: None, desc: "Same as /redirect/{n}, using absolute Location URLs.", curl: "curl -L {base}/absolute-redirect/3" },
            Endpoint { methods: "GET/POST/PUT/PATCH/DELETE/TRACE", path: "/redirect-to", badge: Some(Badge::Enhanced), desc: "Redirects to ?url=; POST/PUT/PATCH/DELETE also accept form/JSON bodies, and browser clients see an anti-phishing interstitial instead of a silent redirect.", curl: "curl -X POST {base}/redirect-to -d 'url=https://example.com'" },
        ],
    },
    Category {
        id: "streaming",
        title: "Streaming",
        desc: "Server-Sent Events and NDJSON streaming endpoints.",
        endpoints: &[
            Endpoint { methods: "GET", path: "/sse", badge: Some(Badge::New), desc: "Streams server-sent events; supports OpenAI-compatible chunk formats.", curl: "curl -N '{base}/sse?count=3&format=simple'" },
            Endpoint { methods: "GET", path: "/sse/{count}", badge: Some(Badge::New), desc: "Same as /sse, with a fixed event count.", curl: "curl -N {base}/sse/5" },
            Endpoint { methods: "GET", path: "/sse/{count}/{delay}", badge: Some(Badge::New), desc: "Same as /sse, with a fixed count and delay between events.", curl: "curl -N {base}/sse/5/1000" },
            Endpoint { methods: "GET", path: "/ndjson", badge: Some(Badge::New), desc: "Streams newline-delimited JSON; supports OpenAI/Ollama-compatible chunk formats.", curl: "curl -N '{base}/ndjson?count=3&format=simple'" },
            Endpoint { methods: "GET", path: "/ndjson/{count}", badge: Some(Badge::New), desc: "Same as /ndjson, with a fixed line count.", curl: "curl -N {base}/ndjson/5" },
            Endpoint { methods: "GET", path: "/ndjson/{count}/{delay}", badge: Some(Badge::New), desc: "Same as /ndjson, with a fixed count and delay between lines.", curl: "curl -N {base}/ndjson/5/1000" },
        ],
    },
    Category {
        id: "llm",
        title: "AI API Mock",
        desc: "Mock OpenAI- and Anthropic-compatible LLM APIs: point an SDK base_url at /llm and test without a paid provider.",
        endpoints: &[
            Endpoint { methods: "GET", path: "/llm", badge: Some(Badge::New), desc: "Self-describing index: endpoints, base_url guidance for both SDK families, and the httpcan response-override contract.", curl: "curl {base}/llm" },
            Endpoint { methods: "POST", path: "/llm/v1/chat/completions", badge: Some(Badge::New), desc: "Mock OpenAI Chat Completions API: canonical chat.completion shape, SSE streaming with [DONE], and an httpcan.content override. /llm/chat/completions works as a silent alias.", curl: "curl -X POST {base}/llm/v1/chat/completions -H 'Content-Type: application/json' -d '{\"model\":\"gpt-5.6-sol\",\"messages\":[{\"role\":\"user\",\"content\":\"Hello\"}]}'" },
            Endpoint { methods: "POST", path: "/llm/v1/messages", badge: Some(Badge::New), desc: "Mock Anthropic Messages API: content blocks, stop_reason, and the full streaming event protocol (message_start through message_stop).", curl: "curl -X POST {base}/llm/v1/messages -H 'Content-Type: application/json' -d '{\"model\":\"claude-sonnet-5\",\"max_tokens\":64,\"messages\":[{\"role\":\"user\",\"content\":\"Hello\"}]}'" },
            Endpoint { methods: "POST", path: "/llm/v1/responses", badge: Some(Badge::New), desc: "Mock OpenAI Responses API: canonical Response object with output_text convenience field; streaming uses named SSE events (response.created through response.completed) with sequence numbers. /llm/responses works as a silent alias.", curl: "curl -X POST {base}/llm/v1/responses -H 'Content-Type: application/json' -d '{\"model\":\"gpt-5.6-sol\",\"input\":\"Hello\"}'" },
            Endpoint { methods: "POST", path: "/llm/v1/completions", badge: Some(Badge::New), desc: "Mock OpenAI legacy Completions API (text-in/text-out): echo support, n choices, and SSE streaming with [DONE]. /llm/completions works as a silent alias.", curl: "curl -X POST {base}/llm/v1/completions -H 'Content-Type: application/json' -d '{\"model\":\"gpt-5.6-sol\",\"prompt\":\"Once upon a time\"}'" },
            Endpoint { methods: "GET", path: "/llm/v1/models", badge: Some(Badge::New), desc: "Model list in the OpenAI shape, or the Anthropic shape when an anthropic-version header is present (both SDKs hit this same path).", curl: "curl {base}/llm/v1/models" },
            Endpoint { methods: "GET", path: "/llm/v1/models/{model}", badge: Some(Badge::New), desc: "Single-model lookup that always returns 200 and echoes the requested id — any model name is valid.", curl: "curl {base}/llm/v1/models/gpt-5.6-sol" },
        ],
    },
    Category {
        id: "oauth2",
        title: "OAuth 2.0 Mock",
        desc: "Mock authorization server: RFC 6749 four grants with PKCE, one-time codes, rotating refresh tokens, and RFC 8414 discovery.",
        endpoints: &[
            Endpoint { methods: "GET", path: "/oauth2", badge: Some(Badge::New), desc: "Self-describing index: endpoints, supported grants, PKCE methods, and the mock's state semantics.", curl: "curl {base}/oauth2" },
            Endpoint { methods: "GET/POST", path: "/oauth2/authorize", badge: Some(Badge::New), desc: "Authorization endpoint with a consent page. response_type=code issues a one-time authorization code (PKCE supported); response_type=token (implicit, legacy) returns the access token in the redirect fragment.", curl: "curl '{base}/oauth2/authorize?response_type=code&client_id=cli&redirect_uri=https%3A%2F%2Fexample.com%2Fcb&state=xyz'" },
            Endpoint { methods: "POST", path: "/oauth2/token", badge: Some(Badge::New), desc: "Token endpoint: authorization_code (+PKCE), password, refresh_token (rotating), and client_credentials grants; Basic and form-body client authentication.", curl: "curl -X POST {base}/oauth2/token -d 'grant_type=client_credentials&client_id=cli&client_secret=s3cr3t'" },
            Endpoint { methods: "GET/POST", path: "/oauth2/userinfo", badge: Some(Badge::New), desc: "Bearer-protected resource: verifies the access token and returns the mock identity (sub/email/client_id/scope).", curl: "curl {base}/oauth2/userinfo -H 'Authorization: Bearer <token>'" },
        ],
    },
    Category {
        id: "observability",
        title: "Observability",
        desc: "Health checks and instance identification.",
        endpoints: &[
            Endpoint { methods: "GET", path: "/healthz", badge: Some(Badge::New), desc: "Liveness probe: returns 200 whenever the server is up.", curl: "curl {base}/healthz" },
            Endpoint { methods: "GET", path: "/tags", badge: Some(Badge::New), desc: "Returns all HTTPCAN_* environment variables, for instance identification.", curl: "curl {base}/tags" },
            Endpoint { methods: "GET", path: "/tags/{name}", badge: Some(Badge::New), desc: "Returns a single HTTPCAN_* environment variable by name.", curl: "curl {base}/tags/VERSION" },
        ],
    },
];

fn escape_html(input: &str) -> String {
    input
        .replace('&', "&amp;")
        .replace('<', "&lt;")
        .replace('>', "&gt;")
        .replace('"', "&quot;")
}

fn badge_html(badge: Option<Badge>) -> String {
    match badge {
        None => String::new(),
        Some(b) => format!(
            r#" <span class="{}" title="{}">{}</span>"#,
            b.css_class(),
            b.title(),
            b.label()
        ),
    }
}

/// Renders the copy-to-clipboard button for an endpoint's example curl
/// command. `base` is the current request's origin, substituted into the
/// endpoint's `{base}`-templated curl string before HTML-escaping.
fn copy_button_html(curl_template: &str, base: &str) -> String {
    let curl = curl_template.replace("{base}", base);
    format!(
        r#" <button type="button" class="copy-btn" data-curl="{}" title="Copy curl example" aria-label="Copy curl example">Copy</button>"#,
        escape_html(&curl)
    )
}

fn render_toc() -> String {
    let mut s = String::new();
    s.push_str("<nav class=\"toc\" aria-label=\"Endpoint categories\">\n");
    for cat in CATEGORIES {
        let _ = writeln!(s, "<a href=\"#{}\">{}</a>", cat.id, escape_html(cat.title));
    }
    s.push_str("</nav>\n");
    s
}

fn render_categories(base: &str) -> String {
    let mut s = String::new();
    for cat in CATEGORIES {
        let _ = write!(
            s,
            "<section id=\"{}\">\n<h2>{} <a class=\"hash\" href=\"#{}\">#</a></h2>\n<p class=\"cat-desc\">{}</p>\n<ul class=\"endpoint-list\">\n",
            cat.id,
            escape_html(cat.title),
            cat.id,
            escape_html(cat.desc)
        );
        for ep in cat.endpoints {
            let _ = writeln!(
                s,
                "<li><code class=\"method\">{}</code> <code class=\"path\">{}</code>{}{}<span class=\"desc\">{}</span></li>",
                escape_html(ep.methods),
                escape_html(ep.path),
                badge_html(ep.badge),
                copy_button_html(ep.curl, base),
                escape_html(ep.desc)
            );
        }
        s.push_str("</ul>\n</section>\n");
    }
    s
}

fn badge_counts() -> (usize, usize, usize) {
    let mut enhanced = 0;
    let mut new = 0;
    // Total counts spec paths (not catalog entries) so the "N-endpoint
    // superset" claim stays arithmetically consistent with /openapi.json —
    // e.g. the compact digest-auth entry covers three spec paths.
    let total = super::openapi::spec_path_count();
    for cat in CATEGORIES {
        for ep in cat.endpoints {
            match ep.badge {
                Some(Badge::Enhanced) => enhanced += 1,
                Some(Badge::New) => new += 1,
                None => {}
            }
        }
    }
    (total, enhanced, new)
}

const STYLE: &str = r#"
:root { color-scheme: light dark; }
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
    margin: 0 auto;
    padding: 0 1.25rem 4rem;
    max-width: 880px;
    font: 17px/1.55 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    color: #1f2328;
    background: #fff;
}
a { color: #0969da; text-decoration: none; }
a:hover { text-decoration: underline; }
header.hero { padding: 2.5rem 0 1rem; }
header.hero h1 { font-size: 2.5rem; margin: 0 0 0.25rem; letter-spacing: -0.02em; }
header.hero p.tagline { margin: 0 0 1rem; opacity: 0.85; font-size: 1.05rem; }
nav.top-links { display: flex; flex-wrap: wrap; gap: 0.75rem 1.25rem; font-size: 0.95rem; }
h2 { font-size: 1.5rem; margin: 2.5rem 0 0.25rem; scroll-margin-top: 1rem; }
h2 .hash { opacity: 0; margin-left: 0.4rem; font-weight: 400; }
h2:hover .hash { opacity: 0.5; }
p.cat-desc { margin: 0 0 0.75rem; opacity: 0.75; }
code { background: #f6f8fa; padding: 0.1rem 0.4rem; border-radius: 4px; font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace; font-size: 0.85em; }
.endpoint-list { list-style: none; margin: 0; padding: 0; }
.endpoint-list li { display: flex; flex-wrap: wrap; align-items: baseline; gap: 0.5rem; padding: 0.4rem 0; border-bottom: 1px dashed rgba(127,127,127,0.25); }
.endpoint-list li:last-child { border-bottom: none; }
.endpoint-list code.method { opacity: 0.6; font-size: 0.75em; min-width: 3.5em; }
.endpoint-list code.path { font-weight: 600; }
.endpoint-list span.desc { flex-basis: 100%; opacity: 0.85; font-size: 0.95em; }
.badge { display: inline-block; font-size: 0.7em; font-weight: 700; text-transform: uppercase; letter-spacing: 0.04em; padding: 0.1rem 0.45rem; border-radius: 999px; }
.badge-enhanced { background: #ddf0ff; color: #0550ae; }
.badge-new { background: #dafbe1; color: #116329; }
.copy-btn { font: inherit; font-size: 0.7em; font-weight: 600; letter-spacing: 0.02em; padding: 0.1rem 0.5rem; border-radius: 5px; border: 1px solid rgba(127,127,127,0.35); background: #f6f8fa; color: inherit; cursor: pointer; line-height: 1.6; opacity: 0; transition: opacity 0.1s; }
.endpoint-list li:hover .copy-btn, .copy-btn:focus-visible, .copy-btn.copied { opacity: 1; }
.copy-btn:hover { background: #eaeef2; }
.copy-btn.copied { background: #dafbe1; border-color: #2ea043; color: #116329; }
.toc { display: flex; flex-wrap: wrap; gap: 0.5rem 1rem; margin: 1rem 0 2rem; font-size: 0.95rem; }
.highlights, pre { background: #f6f8fa; border: 1px solid rgba(127,127,127,0.2); border-radius: 8px; padding: 1rem 1.25rem; }
.highlights ul { margin: 0.5rem 0 0; padding-left: 1.2rem; }
.highlights li { margin: 0.35rem 0; }
.legend { display: flex; flex-wrap: wrap; gap: 1.25rem; align-items: center; font-size: 0.9rem; opacity: 0.9; margin: 1rem 0 0; }
pre { overflow-x: auto; margin: 0.5rem 0; }
pre code { background: none; padding: 0; font-size: 0.85em; }
footer { margin-top: 3rem; padding-top: 1.5rem; border-top: 1px solid rgba(127,127,127,0.2); font-size: 0.9rem; opacity: 0.85; }
footer p { margin: 0.35rem 0; }
/* Dark overrides: MUST stay after the light rules above — equal specificity,
   so the later rule wins and these take precedence in dark mode. */
@media (prefers-color-scheme: dark) {
    body { color: #e6edf3; background: #0d1117; }
    a { color: #58a6ff; }
    .badge-enhanced { background: #1f3a5f; color: #9ecbff; }
    .badge-new { background: #123a24; color: #7ee2a8; }
    code { background: #161b22; }
    .highlights, pre { background: #161b22; border-color: #30363d; }
    footer { border-color: #30363d; }
    .copy-btn { background: #161b22; border-color: #30363d; color: #e6edf3; }
    .copy-btn:hover { background: #21262d; }
    .copy-btn.copied { background: #123a24; border-color: #2ea043; color: #7ee2a8; }
}
/* No hover on touch devices: keep copy buttons visible instead of opacity:0. */
@media (hover: none) {
    .copy-btn { opacity: 1; }
}
"#;

/// Vanilla JS, no dependencies: copies the clicked endpoint's `data-curl`
/// attribute to the clipboard, with a `document.execCommand` fallback for
/// non-secure contexts (e.g. testing over plain HTTP on a LAN).
const SCRIPT: &str = r#"
function httpcanCopyText(text) {
    if (navigator.clipboard && window.isSecureContext) {
        return navigator.clipboard.writeText(text);
    }
    var ta = document.createElement('textarea');
    ta.value = text;
    ta.style.position = 'fixed';
    ta.style.opacity = '0';
    document.body.appendChild(ta);
    ta.focus();
    ta.select();
    try { document.execCommand('copy'); } finally { document.body.removeChild(ta); }
    return Promise.resolve();
}
document.addEventListener('click', function (event) {
    var btn = event.target.closest('.copy-btn');
    if (!btn) return;
    httpcanCopyText(btn.getAttribute('data-curl')).then(function () {
        var previous = btn.textContent;
        btn.textContent = 'Copied!';
        btn.classList.add('copied');
        setTimeout(function () {
            btn.textContent = previous;
            btn.classList.remove('copied');
        }, 1200);
    });
});
"#;

fn render_homepage(canonical_url: &str, base: &str, version: &str) -> String {
    let (total, enhanced, new) = badge_counts();
    format!(
        r##"<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>HTTPCan &mdash; httpbin Alternative with AI &amp; OAuth2 Mocks</title>
<meta name="description" content="A Rust superset of httpbin.org: {total} drop-in endpoints, mock OpenAI/Anthropic LLM APIs, and a full OAuth 2.0 server — for testing HTTP clients and AI agents.">
<link rel="canonical" href="{canonical_url}">
<link rel="icon" type="image/png" href="/favicon.png">
<style>{style}</style>
</head>
<body>
<header class="hero">
<h1>HTTPCan</h1>
<p class="tagline">A modern, high-performance superset of <a href="https://httpbin.org">httpbin.org</a> for testing HTTP clients, proxies, and AI agents &mdash; with mock OpenAI/Anthropic LLM APIs and a full OAuth 2.0 server. Built with Rust and Actix Web.</p>
<nav class="top-links">
<a href="#quick-start">Quick Start</a>
<a href="#why-httpcan">Why HTTPCan</a>
<a href="/openapi.json">OpenAPI Spec</a>
<a href="https://github.com/seedvector/httpcan">GitHub</a>
</nav>
</header>

<section id="quick-start">
<h2>Quick Start <a class="hash" href="#quick-start">#</a></h2>
<p>You're on a live instance &mdash; <code>{base}</code>. Try an endpoint now:</p>
<pre><code>curl {base}/get</code></pre>
<p id="self-host">Want your own? Run HTTPCan locally or in production:</p>
<pre><code># Docker
docker run -p 8080:8080 ghcr.io/seedvector/httpcan:latest

# Cargo
cargo install httpcan &amp;&amp; httpcan

curl http://localhost:8080/get</code></pre>
</section>

<section id="why-httpcan">
<h2>Why HTTPCan <a class="hash" href="#why-httpcan">#</a></h2>
<div class="highlights">
<p>HTTPCan is a <strong>{total}-endpoint superset of httpbin.org</strong>: every httpbin.org endpoint is covered and drop-in compatible, plus {new} endpoints httpbin.org doesn't have and {enhanced} it has but httpcan fixes or extends (see the badges below). On top of that:</p>
<ul>
<li><strong>AI API mock</strong> &mdash; OpenAI- and Anthropic-compatible <code>/llm</code> endpoints: point any SDK <code>base_url</code> at it (streaming included) and test AI clients without a paid provider.</li>
<li><strong>OAuth 2.0 mock</strong> &mdash; a full authorization server at <code>/oauth2</code>: four RFC 6749 grants with PKCE, one-time codes, rotating refresh tokens, Bearer-protected userinfo, and RFC 8414 discovery.</li>
<li><strong>AI-friendly streaming</strong> &mdash; native <code>/sse</code> and <code>/ndjson</code> endpoints with OpenAI/Ollama-compatible chunk formats.</li>
<li><strong>Measured performance</strong> &mdash; in our benchmarks against comparable HTTP testing servers, HTTPCan led on both throughput and tail latency.</li>
<li><strong>Anti-phishing redirects</strong> &mdash; browser clients hitting <code>/redirect-to</code> see a confirmation page instead of a silent 302, closing an open-redirect abuse vector.</li>
<li><strong>Correct header handling</strong> &mdash; duplicate and non-ASCII request headers are preserved instead of being dropped or crashing the server.</li>
<li><strong>Safer by default</strong> &mdash; built-in filtering strips ~100 reverse-proxy/CDN headers from echoed responses, with <code>--exclude-headers</code> for more.</li>
<li><strong>Cloud-native observability</strong> &mdash; <code>/healthz</code> liveness probe, <code>/tags</code> instance identification, and <code>Server-Timing</code>/<code>X-Httpcan-Version</code> on every response.</li>
</ul>
<p class="legend">
<span><span class="badge badge-enhanced">Enhanced</span> &nbsp;{enhanced} endpoints httpbin has, but httpcan fixes or extends</span>
<span><span class="badge badge-new">New</span> &nbsp;{new} endpoints not available in httpbin.org</span>
<span>no badge &nbsp;drop-in compatible with httpbin.org</span>
</p>
</div>
</section>

<section id="endpoints">
<h2>Endpoints <a class="hash" href="#endpoints">#</a></h2>
<p class="cat-desc">Each endpoint has a <strong>Copy</strong> button with a ready-to-run curl example (with parameters filled in) targeting this instance.</p>
{toc}
{categories}
</section>

<footer>
<p>HTTPCan &middot; version {version} &middot; MIT License</p>
<p><a href="/openapi.json">OpenAPI spec</a> &middot; <a href="https://github.com/seedvector/httpcan">Source on GitHub</a> &middot; <a href="https://github.com/seedvector/httpcan/issues">Report an issue</a></p>
</footer>
<script>{script}</script>
</body>
</html>"##,
        canonical_url = canonical_url,
        style = STYLE,
        total = total,
        enhanced = enhanced,
        new = new,
        toc = render_toc(),
        categories = render_categories(base),
        base = escape_html(base),
        version = version,
        script = SCRIPT,
    )
}

/// Escapes `|` so a value is safe inside a Markdown table cell. Cell content
/// here is single-line, so only the column-delimiting pipe needs escaping.
fn md_table_escape(cell: &str) -> String {
    cell.replace('|', "\\|")
}

/// Renders the homepage as Markdown for AI agents that send
/// `Accept: text/markdown` (Content-Type: text/markdown). Mirrors the HTML
/// page — intro, quick start, highlights, and every endpoint grouped by
/// category with runnable curl examples resolved against `base` — so agents
/// get clean text instead of scraping dense HTML. See
/// <https://developers.cloudflare.com/fundamentals/reference/markdown-for-agents/>.
fn render_markdown(base: &str, version: &str) -> String {
    let (total, enhanced, new) = badge_counts();
    let mut s = String::new();

    let _ = writeln!(
        s,
        "# HTTPCan\n\nA modern, high-performance superset of [httpbin.org](https://httpbin.org) for testing HTTP clients, proxies, and AI agents — with mock OpenAI/Anthropic LLM APIs and a full OAuth 2.0 server. Built with Rust and Actix Web.\n"
    );
    let _ = writeln!(s, "- [OpenAPI spec]({base}/openapi.json)");
    let _ = writeln!(
        s,
        "- [Source on GitHub](https://github.com/seedvector/httpcan)\n"
    );

    let _ = writeln!(s, "## Quick Start\n");
    let _ = writeln!(
        s,
        "You're on a live instance — `{base}`. Try an endpoint now:\n"
    );
    let _ = writeln!(s, "```sh");
    let _ = writeln!(s, "curl {base}/get");
    let _ = writeln!(s, "```\n");
    let _ = writeln!(s, "Want your own? Run HTTPCan locally or in production:\n");
    let _ = writeln!(s, "```sh");
    let _ = writeln!(s, "# Docker");
    let _ = writeln!(
        s,
        "docker run -p 8080:8080 ghcr.io/seedvector/httpcan:latest\n"
    );
    let _ = writeln!(s, "# Cargo");
    let _ = writeln!(s, "cargo install httpcan && httpcan\n");
    let _ = writeln!(s, "curl http://localhost:8080/get");
    let _ = writeln!(s, "```\n");

    let _ = writeln!(s, "## Why HTTPCan\n");
    let _ = writeln!(
        s,
        "HTTPCan is a **{total}-endpoint superset of httpbin.org**: every httpbin.org endpoint is covered and drop-in compatible, plus {new} endpoints httpbin.org doesn't have and {enhanced} it has but httpcan fixes or extends.\n"
    );
    let _ = writeln!(s, "- **AI API mock** — OpenAI- and Anthropic-compatible `/llm` endpoints: point any SDK `base_url` at it (streaming included) and test AI clients without a paid provider.");
    let _ = writeln!(s, "- **OAuth 2.0 mock** — a full authorization server at `/oauth2`: four RFC 6749 grants with PKCE, one-time codes, rotating refresh tokens, Bearer-protected userinfo, and RFC 8414 discovery.");
    let _ = writeln!(s, "- **AI-friendly streaming** — native `/sse` and `/ndjson` endpoints with OpenAI/Ollama-compatible chunk formats.");
    let _ = writeln!(s, "- **Measured performance** — in our benchmarks against comparable HTTP testing servers, HTTPCan led on both throughput and tail latency.");
    let _ = writeln!(s, "- **Anti-phishing redirects** — browser clients hitting `/redirect-to` see a confirmation page instead of a silent 302, closing an open-redirect abuse vector.");
    let _ = writeln!(s, "- **Correct header handling** — duplicate and non-ASCII request headers are preserved instead of being dropped or crashing the server.");
    let _ = writeln!(s, "- **Safer by default** — built-in filtering strips ~100 reverse-proxy/CDN headers from echoed responses, with `--exclude-headers` for more.");
    let _ = writeln!(
        s,
        "- **Cloud-native observability** — `/healthz` liveness probe, `/tags` instance identification, and `Server-Timing`/`X-Httpcan-Version` on every response.\n"
    );
    let _ = writeln!(
        s,
        "> **{enhanced}** Enhanced (httpbin has it; httpcan fixes/extends) · **{new}** New (not in httpbin.org) · no badge = drop-in compatible.\n"
    );

    let _ = writeln!(s, "## Endpoints\n");
    let _ = writeln!(s, "All examples below target this instance (`{base}`).\n");
    for cat in CATEGORIES {
        let _ = writeln!(s, "### {}\n", cat.title);
        let _ = writeln!(s, "{}\n", cat.desc);
        let _ = writeln!(s, "| Method | Path | Description | Example |");
        let _ = writeln!(s, "| --- | --- | --- | --- |");
        for ep in cat.endpoints {
            let badge = match ep.badge {
                Some(Badge::Enhanced) => " _(Enhanced)_",
                Some(Badge::New) => " _(New)_",
                None => "",
            };
            let desc = format!("{}{badge}", ep.desc);
            let example = ep.curl.replace("{base}", base);
            let _ = writeln!(
                s,
                "| `{}` | `{}` | {} | `{}` |",
                md_table_escape(ep.methods),
                md_table_escape(ep.path),
                md_table_escape(&desc),
                md_table_escape(&example)
            );
        }
        let _ = writeln!(s);
    }

    let _ = writeln!(s, "---\n");
    let _ = writeln!(
        s,
        "HTTPCan · version {version} · {total} endpoints · MIT License\n"
    );

    s
}

/// Returns true when the client explicitly asks for Markdown via
/// `Accept: text/markdown`. Mirrors the Accept parsing used by the `/image`
/// endpoint; browsers and crawlers that don't request Markdown keep getting
/// the HTML page.
fn wants_markdown(req: &HttpRequest) -> bool {
    req.headers()
        .get("accept")
        .and_then(|h| h.to_str().ok())
        .map(|a| a.to_lowercase().contains("text/markdown"))
        .unwrap_or(false)
}

/// Adds RFC 8288 / RFC 9727 `Link` headers to the homepage response so agents
/// can discover HTTPCan's machine-readable resources without scraping HTML:
/// the API catalog (`api-catalog`, RFC 9727 §3), the OpenAPI spec
/// (`service-desc`, RFC 8631) which also describes the resource (`describedby`,
/// RFC 8288), and the human-readable docs (`service-doc`, RFC 8631). Targets
/// are relative refs resolved against the request URI, and each header carries
/// a single relation type for broad parser compatibility.
fn add_homepage_link_headers(
    mut res: actix_web::HttpResponseBuilder,
) -> actix_web::HttpResponseBuilder {
    res.append_header(("Link", "</.well-known/api-catalog>; rel=\"api-catalog\""));
    res.append_header(("Link", "</openapi.json>; rel=\"service-desc\""));
    res.append_header(("Link", "</>; rel=\"service-doc\""));
    res.append_header(("Link", "</openapi.json>; rel=\"describedby\""));
    res
}

/// Homepage: a fully server-rendered, static HTML page describing HTTPCan and
/// listing every endpoint grouped by category, with a compatibility badge
/// relative to httpbin.org and a one-click "Copy" button for a ready-to-run
/// curl example.
///
/// Content negotiation (Markdown for Agents): a request carrying
/// `Accept: text/markdown` gets the same content rendered as Markdown with
/// `Content-Type: text/markdown` and an estimated `x-markdown-tokens` count,
/// so AI agents receive clean text instead of scraping HTML. Every other
/// request — browsers, search engines, AI crawlers — gets the HTML page (see
/// `/openapi.json` for the machine-readable spec).
///
/// Every homepage response also carries RFC 8288 / RFC 9727 `Link` headers
/// (api-catalog, service-desc, service-doc, describedby) so agents can discover
/// the machine-readable resources without scraping the page.
pub async fn root_handler(req: HttpRequest, config: web::Data<AppConfig>) -> Result<HttpResponse> {
    // User override: `static/index.html` replaces the built-in homepage at
    // `/`. It forfeits the dynamic parts (origin-resolved curl examples,
    // markdown negotiation, RFC 8288 Link headers, canonical URL) — the
    // operator's file is served verbatim.
    if let Some(file) = static_override(&config, "index.html") {
        return Ok(file.into_response(&req));
    }
    // `base` mirrors the scheme/host the visitor actually used, so curl
    // examples and copy-paste links stay usable as-is (an https visitor gets
    // https examples, a plain-http visitor — e.g. local dev, or a self-hosted
    // instance without TLS — gets http examples that actually work).
    let connection_info = req.connection_info();
    let base = format!("{}://{}", connection_info.scheme(), connection_info.host());
    // The canonical link is a pure SEO signal, not something a user copies
    // to run — it should stay stable regardless of how this particular
    // request arrived, so it honors `scheme_override` instead of mirroring it.
    let canonical_url = format!("{}/", resolved_base(&req, &config));
    let version = option_env!("CARGO_PKG_VERSION").unwrap_or("unknown");

    if wants_markdown(&req) {
        let body = render_markdown(&base, version);
        // Rough estimate (~4 chars/token); exact counts need a BPE tokenizer.
        let tokens = body.chars().count() / 4;
        return Ok(add_homepage_link_headers(HttpResponse::Ok())
            .content_type("text/markdown; charset=utf-8")
            .insert_header(("x-markdown-tokens", tokens.to_string()))
            .body(body));
    }

    Ok(add_homepage_link_headers(HttpResponse::Ok())
        .content_type("text/html; charset=utf-8")
        .body(render_homepage(&canonical_url, &base, version)))
}

/// `/favicon.png` — embedded in the binary so the default experience is fully
/// self-contained (the built-in homepage references it in `<head>`). A file
/// named `favicon.png` in the static assets directory overrides it, e.g. for
/// custom-branded deployments.
const EMBEDDED_FAVICON: &[u8] = include_bytes!("../../static/favicon.png");

pub async fn favicon_handler(
    req: HttpRequest,
    config: web::Data<AppConfig>,
) -> Result<HttpResponse> {
    if let Some(file) = static_override(&config, "favicon.png") {
        return Ok(file.into_response(&req));
    }
    Ok(HttpResponse::Ok()
        .content_type(mime::IMAGE_PNG)
        .body(EMBEDDED_FAVICON))
}