squeeze-lib 1.0.0

//! URI finder implementation based on [RFC 3986](https://tools.ietf.org/html/rfc3986#appendix-A).
//!
//! This module provides a [`URI`] finder that can extract URIs from text, optionally
//! filtering by scheme (http, https, mailto, etc.).
//!
//! # Example
//!
//! ```
//! use squeeze::{uri::URI, Finder};
//!
//! let mut finder = URI::default();
//! finder.add_scheme("https"); // Only match https URLs
//!
//! let text = "Visit https://example.com or http://other.com";
//! if let Some(range) = finder.find(text) {
//!     assert_eq!(&text[range], "https://example.com");
//! }
//! ```

use super::Finder;
use std::ops::Range;

const SUB_DELIMS_STRICT: [bool; 256] = {
    let mut table = [false; 256];
    table[b'!' as usize] = true;
    table[b'$' as usize] = true;
    table[b'&' as usize] = true;
    table[b'\'' as usize] = true;
    table[b'(' as usize] = true;
    table[b')' as usize] = true;
    table[b'*' as usize] = true;
    table[b'+' as usize] = true;
    table[b',' as usize] = true;
    table[b';' as usize] = true;
    table[b'=' as usize] = true;
    table
};

const SUB_DELIMS_LAX: [bool; 256] = {
    let mut table = [false; 256];
    table[b'!' as usize] = true;
    table[b'$' as usize] = true;
    table[b'&' as usize] = true;
    table[b'(' as usize] = true;
    table[b'*' as usize] = true;
    table[b'+' as usize] = true;
    table[b',' as usize] = true;
    table[b';' as usize] = true;
    table[b'=' as usize] = true;
    table
};

/// Byte classes of the URI body, one table per mode: `PCHAR` is
/// unreserved / sub-delims / ":" / "@" (plus ")" in lax mode), `QUERY` adds
/// "/" and "?", `USERINFO` is unreserved / sub-delims / ":". Percent
/// encoding is handled separately.
const PCHAR: u8 = 1 << 0;
const QUERY: u8 = 1 << 1;
const USERINFO: u8 = 1 << 2;
/// Hostname label bytes: ASCII alphanumerics, `_` and `-`.
const LABEL: u8 = 1 << 3;

const fn body_classes(strict: bool) -> [u8; 256] {
    let mut table = [0u8; 256];
    let mut b = 0usize;
    while b < 256 {
        let c = b as u8;
        let unreserved =
            c.is_ascii_alphanumeric() || c == b'-' || c == b'.' || c == b'_' || c == b'~';
        let sub_delim = if strict {
            SUB_DELIMS_STRICT[b]
        } else {
            SUB_DELIMS_LAX[b]
        };
        let mut flags = 0u8;
        if unreserved || sub_delim || c == b':' {
            flags |= USERINFO;
        }
        if unreserved || sub_delim || c == b':' || c == b'@' || (!strict && c == b')') {
            flags |= PCHAR;
        }
        if flags & PCHAR != 0 || c == b'/' || c == b'?' {
            flags |= QUERY;
        }
        if c.is_ascii_alphanumeric() || c == b'_' || c == b'-' {
            flags |= LABEL;
        }
        table[b] = flags;
        b += 1;
    }
    table
}

static BODY_CLASSES_STRICT: [u8; 256] = body_classes(true);
static BODY_CLASSES_LAX: [u8; 256] = body_classes(false);

// Covers every IANA-registered scheme (the longest is 36 bytes) so opaque
// URIs using them are not truncated out of the registry lookup.
const MAX_SCHEME_LEN: usize = 64;

#[derive(Default, Clone, Copy)]
struct SchemeConfig(u8);

impl SchemeConfig {
    fn has(&self, flag: u8) -> bool {
        (self.0 & flag) != 0
    }
}

/// Per-scheme parsing rules, ASCII case ignored.
fn scheme_config(scheme: &str) -> SchemeConfig {
    if ["ftp", "http", "https"]
        .iter()
        .any(|s| scheme.eq_ignore_ascii_case(s))
    {
        SchemeConfig(DISALLOW_EMPTY_HOST)
    } else {
        SchemeConfig::default()
    }
}

/// Whether the two bytes before a colon can end a registered scheme (ASCII
/// case-insensitive). In lax mode an unregistered scheme needs `//` after
/// the colon, so a colon followed by anything else can only start a URI
/// when this says so: an O(1) rejection of every timestamp and `key:value`
/// colon before the scheme is walked back.
fn can_end_registered_scheme(prev2: u8, prev1: u8) -> bool {
    static TABLE: std::sync::OnceLock<Box<[u64; 1024]>> = std::sync::OnceLock::new();
    let table = TABLE.get_or_init(|| {
        let mut table = Box::new([0u64; 1024]);
        let mut set = |a: u8, b: u8| {
            let index = usize::from(a) << 8 | usize::from(b);
            table[index >> 6] |= 1 << (index & 63);
        };
        for scheme in crate::iana::URI_SCHEMES.iter() {
            let bytes = scheme.as_bytes();
            match bytes {
                [] => {}
                [only] => {
                    for a in 0..=255u8 {
                        set(a, *only);
                    }
                }
                [.., a, b] => set(*a, *b),
            }
        }
        table
    });
    let index =
        usize::from(prev2.to_ascii_lowercase()) << 8 | usize::from(prev1.to_ascii_lowercase());
    table[index >> 6] & (1 << (index & 63)) != 0
}

fn is_registered_scheme(scheme: &str) -> bool {
    crate::registry::uri_schemes().contains(scheme.as_bytes())
}

const DISALLOW_EMPTY_HOST: u8 = 1 << 0;

/// A finder that extracts URIs from text according to RFC 3986.
///
/// By default, any scheme is matched, subject to the lax-mode heuristics
/// below. Use [`URI::add_scheme`] to filter by specific schemes.
///
/// # Strict Mode
///
/// By default, the finder excludes `'` characters, unbalanced trailing `)`
/// characters (so markdown links `[text](url)` work while
/// `…/Sport_(disambiguation)` stays intact), and trailing sentence
/// punctuation (`.,;:!?`) from URIs. It also skips prose and code that
/// happens to parse as a URI: bare `scheme:` labels, `a::b` paths, and opaque
/// URIs (no `//` after the colon) whose scheme is neither IANA-registered nor
/// added with [`URI::add_scheme`]. Set [`URI::strict`] to `true` to strictly
/// follow RFC 3986.
#[derive(Default)]
pub struct URI {
    schemes: Vec<String>,
    /// Last bytes of the allowlisted schemes, a 256-bit set.
    scheme_ends: [u64; 4],
    /// When `true`, strictly follows RFC 3986: any scheme matches and
    /// trailing `'`, `)`, and punctuation are kept.
    /// When `false` (default), applies the text-extraction heuristics above.
    pub strict: bool,
}

impl Finder for URI {
    fn id(&self) -> &'static str {
        "uri"
    }

    fn triggerable(&self) -> bool {
        true
    }

    fn line_agnostic(&self) -> bool {
        // Every walk stops at whitespace, which includes line terminators.
        true
    }

    fn could_trigger_at(&self, byte: u8) -> bool {
        byte == b':'
    }

    fn could_start_after(&self, prev: u8, _cur: u8) -> bool {
        // `rlook_scheme` needs at least one scheme byte right before the colon.
        Self::is_alpha(prev) || Self::is_digit(prev) || matches!(prev, b'+' | b'-' | b'.')
    }

    fn could_continue_with(&self, _cur: u8, next: u8) -> bool {
        if self.strict {
            return true;
        }
        // Lax mode: a second colon marks a code path, and a byte that cannot
        // begin a hier-part, query or fragment leaves a prose-only tail.
        next.is_ascii_alphanumeric()
            || matches!(
                next,
                b'-' | b'.'
                    | b'_'
                    | b'~'
                    | b'%'
                    | b'!'
                    | b'$'
                    | b'&'
                    | b'\''
                    | b'('
                    | b')'
                    | b'*'
                    | b'+'
                    | b','
                    | b';'
                    | b'='
                    | b'@'
                    | b'/'
                    | b'?'
                    | b'#'
            )
    }

    fn has_trigger_context(&self) -> bool {
        // An allowlisted scheme, or in lax mode a registered one unless `//`
        // follows, ends right before the colon: the two bytes before it
        // reject most colons, and the scanner tabulates that once.
        !self.strict || !self.schemes.is_empty()
    }

    // Both mirror the first tests of `try_at_colon`.
    fn trigger_context(&self, prev2: u8, prev1: u8) -> bool {
        if !self.schemes.is_empty() {
            let (prev2, prev1) = (prev2.to_ascii_lowercase(), prev1.to_ascii_lowercase());
            if self.scheme_ends[usize::from(prev1 >> 6)] & (1 << (prev1 & 63)) == 0 {
                return false;
            }
            return self.schemes.iter().any(|s| match s.as_bytes() {
                [] => false,
                [only] => *only == prev1,
                [.., a, b] => *a == prev2 && *b == prev1,
            });
        }
        self.strict || can_end_registered_scheme(prev2, prev1)
    }

    fn trigger_context_exempt(&self, next: Option<u8>) -> bool {
        self.schemes.is_empty() && next == Some(b'/')
    }

    fn try_trigger_at(&self, input: &[u8], pos: usize) -> Option<Range<usize>> {
        self.try_at_colon(input, pos)
    }

    // scheme ":" hier-part [ "?" query ] [ "#" fragment ]
    fn find(&self, s: &str) -> Option<Range<usize>> {
        let input = s.as_bytes();
        let mut idx = 0;

        while idx < input.len() {
            let colon_idx = idx + input[idx..].iter().position(|&b| b == b':')?;
            idx = colon_idx + 1;
            if let Some(range) = self.try_at_colon(input, colon_idx) {
                return Some(range);
            }
        }

        None
    }
}

impl URI {
    /// Adds a scheme to the filter list.
    ///
    /// When at least one scheme is added, only URIs with matching schemes will be found.
    /// Scheme matching is case-insensitive.
    ///
    /// # Example
    ///
    /// ```
    /// use squeeze::{uri::URI, Finder};
    ///
    /// let mut finder = URI::default();
    /// finder.add_scheme("https");
    /// finder.add_scheme("mailto");
    ///
    /// // Will match https:// and mailto: URIs, but not http:// or ftp://
    /// ```
    pub fn add_scheme(&mut self, s: &str) {
        let lower = s.to_lowercase();
        if let Some(&last) = lower.as_bytes().last() {
            self.scheme_ends[usize::from(last >> 6)] |= 1 << (last & 63);
        }
        if let Err(pos) = self.schemes.binary_search(&lower) {
            self.schemes.insert(pos, lower);
        }
    }

    fn try_at_colon(&self, input: &[u8], colon_idx: usize) -> Option<Range<usize>> {
        if input[colon_idx] != b':' {
            return None;
        }

        // Lax mode without an allowlist: anything but `//` after the colon
        // requires a registered scheme, whose last two bytes sit right
        // before the colon. Checked first, before any walk.
        if !self.strict
            && self.schemes.is_empty()
            && input.get(colon_idx + 1) != Some(&b'/')
            && colon_idx >= 1
        {
            let prev1 = input[colon_idx - 1];
            let prev2 = if colon_idx >= 2 {
                input[colon_idx - 2]
            } else {
                b' '
            };
            if !can_end_registered_scheme(prev2, prev1) {
                return None;
            }
        }

        let scheme_idx = self.rlook_scheme(&input[..colon_idx])?;
        let scheme = std::str::from_utf8(&input[scheme_idx..colon_idx]).ok()?;
        // Check the scheme allowlist before parsing the rest of the URI.
        if !self.schemes.is_empty() && !self.schemes.iter().any(|s| s.eq_ignore_ascii_case(scheme))
        {
            return None;
        }
        // Lax mode without an allowlist: a scheme not followed by `//` must
        // be registered. Decided here rather than after the parse, so
        // `localhost:8080` costs one registry lookup.
        if !self.strict
            && self.schemes.is_empty()
            && !input[colon_idx + 1..].starts_with(b"//")
            && !is_registered_scheme(scheme)
        {
            return None;
        }
        let scheme_config = scheme_config(scheme);

        // "Self::Error", "io::Result", "db8::/32": in lax mode a second colon
        // marks a code path or an IPv6 tail, not a URI.
        if !self.strict && input.get(colon_idx + 1) == Some(&b':') {
            return None;
        }

        let mut idx = colon_idx + 1;
        let hier_len = self.look_hier_part(&input[idx..], scheme_config)?;
        idx += hier_len;
        idx += self.look_question_mark_query(&input[idx..]).unwrap_or(0);
        idx += self.look_sharp_fragment(&input[idx..]).unwrap_or(0);

        if !self.strict {
            idx = Self::trim_lax(input, colon_idx, idx);
            let tail = &input[colon_idx + 1..idx];
            // A bare "scheme:" or a punctuation-only tail is prose ("TODO:",
            // "Note: …").
            if tail
                .iter()
                .all(|&b| matches!(b, b'.' | b',' | b';' | b':' | b'!' | b'?' | b'#'))
            {
                return None;
            }
            // An empty hier-part ("magnet:?xt=…") is only trusted at the start
            // of the input or after prose (whitespace, quotes, opening
            // brackets…). Glued to URI innards ("?q=x:?y", "a:=x:#y", …) it is
            // junk — and accepting it would desynchronize trigger dispatch
            // from slice-based find() restarts.
            if hier_len == 0 && scheme_idx > 0 && !Self::is_prose_delimiter(input[scheme_idx - 1]) {
                return None;
            }
            // Without "//", "key:value", "main.rs:42" and "${VAR:-x}" parse
            // as opaque URIs; only trust schemes the user asked for or IANA
            // registered.
            if self.schemes.is_empty() && !tail.starts_with(b"//") && !is_registered_scheme(scheme)
            {
                return None;
            }
        }

        Some(scheme_idx..idx)
    }

    /// Lax-mode cleanup of a parsed candidate: cut at the first `)` that has
    /// no matching `(` inside the candidate, then drop trailing punctuation
    /// that is almost certainly prose. Never trims past the scheme colon.
    fn trim_lax(input: &[u8], colon_idx: usize, mut end: usize) -> usize {
        let body_start = colon_idx + 1;

        // Only a body holding ")" needs its parentheses balanced.
        if memchr::memchr(b')', &input[body_start..end]).is_some() {
            let mut depth = 0usize;
            for (i, &b) in input[body_start..end].iter().enumerate() {
                match b {
                    b'(' => depth += 1,
                    b')' => {
                        if depth == 0 {
                            end = body_start + i;
                            break;
                        }
                        depth -= 1;
                    }
                    _ => {}
                }
            }
        }

        while end > body_start && matches!(input[end - 1], b'.' | b',' | b';' | b':' | b'!' | b'?')
        {
            end -= 1;
        }

        end
    }

    // Bytes that cannot appear inside a lax URI match; a bare "scheme:" is
    // only accepted right after one of these (or at the start of the input).
    #[inline]
    fn is_prose_delimiter(b: u8) -> bool {
        b <= b' '
            || b >= 0x80
            || matches!(
                b,
                b'"' | b'\'' | b'<' | b'>' | b'\\' | b'^' | b'`' | b'{' | b'|' | b'}' | b'(' | b'['
            )
    }

    // ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )
    fn rlook_scheme(&self, input: &[u8]) -> Option<usize> {
        let start = input.len().saturating_sub(MAX_SCHEME_LEN);
        let mut idx = None;
        let mut run_start = input.len();
        for (i, &c) in input[start..].iter().enumerate().rev() {
            if Self::is_alpha(c) {
                idx = Some(start + i);
                run_start = start + i;
            } else if Self::is_digit(c) || c == b'+' || c == b'-' || c == b'.' {
                run_start = start + i;
            } else {
                break;
            }
        }
        // A run glued to leading digits ("2024-01-15T10:") is a number, not a
        // scheme. Runs starting with "." / "+" / "-" still anchor on their
        // first ALPHA ("(http://x", "-http://x").
        if run_start < input.len() && Self::is_digit(input[run_start]) {
            return None;
        }
        idx
    }

    // hier-part = "//" authority path-abempty
    //           / path-absolute
    //           / path-rootless
    //           / path-empty
    fn look_hier_part(&self, input: &[u8], sc: SchemeConfig) -> Option<usize> {
        // "//" authority path-abempty
        // When the input starts with "//" this is the only valid production:
        // path-absolute requires a non-empty first segment, so a failed
        // authority must reject the candidate instead of degrading to a
        // "scheme:/" stub.
        if let Some(idx) = self.look_slash_slash(input) {
            let idx = idx + self.look_authority(&input[idx..], sc)?;
            return Some(idx + self.look_path_abempty(&input[idx..]));
        }

        // Some schemes disallow empty hosts
        if sc.has(DISALLOW_EMPTY_HOST) {
            return None;
        }

        // "/" [ segment-nz path-abempty ]
        if let Some(idx) = self.look_slash(input).map(|idx| {
            idx + self
                .look_segment_nz(&input[idx..])
                .map(|i| i + self.look_path_abempty(&input[idx + i..]))
                .unwrap_or(0)
        }) {
            return Some(idx);
        }

        // segment-nz path-abempty
        if let Some(idx) = self
            .look_segment_nz(input)
            .map(|idx| idx + self.look_path_abempty(&input[idx..]))
        {
            return Some(idx);
        }

        // 0<pchar>
        Some(0)
    }

    // [ userinfo "@" ] host [ ":" port ]
    fn look_authority(&self, input: &[u8], sc: SchemeConfig) -> Option<usize> {
        let mut idx = 0;
        idx += self.look_userinfo_at(&input[idx..]).unwrap_or(0);
        idx += self
            .look_host(&input[idx..])
            .filter(|&i| !(i == 0 && sc.has(DISALLOW_EMPTY_HOST)))?;
        if let Some(i) = self.look_colon(&input[idx..]) {
            idx += i;
            let port_len = self.look_port(&input[idx..]);
            idx += port_len;
            // A port glued to further scheme-run characters ("…:80foo") would
            // end the match mid-token; reject the candidate instead so the
            // Scanner and slice-based find() restarts stay in sync.
            let glued = input.get(idx).is_some_and(|&b| {
                b.is_ascii_alphanumeric() || b == b'+' || b == b'-' || (b == b'.' && port_len > 0)
            });
            if glued {
                return None;
            }
        }
        Some(idx)
    }

    // *( "/" segment )
    fn look_path_abempty(&self, input: &[u8]) -> usize {
        let mut idx = 0;
        while idx < input.len() {
            idx += match self
                .look_slash(&input[idx..])
                .map(|i| i + self.look_segment(&input[idx + i..]))
            {
                Some(n) => n,
                None => break,
            };
        }
        idx
    }

    // *pchar
    fn look_segment(&self, input: &[u8]) -> usize {
        self.look_run(input, PCHAR)
    }

    /// Length of the run of bytes in the body class `class` or
    /// percent-encoded triples starting `input`.
    #[inline]
    fn look_run(&self, input: &[u8], class: u8) -> usize {
        let table = self.body_classes();
        let mut idx = 0;
        while idx < input.len() {
            let b = input[idx];
            if table[b as usize] & class != 0 {
                idx += 1;
            } else if b == b'%' {
                match self.look_pct_encoded(&input[idx..]) {
                    Some(n) => idx += n,
                    None => break,
                }
            } else {
                break;
            }
        }
        idx
    }

    #[inline]
    fn body_classes(&self) -> &'static [u8; 256] {
        if self.strict {
            &BODY_CLASSES_STRICT
        } else {
            &BODY_CLASSES_LAX
        }
    }

    // 1*pchar
    fn look_segment_nz(&self, input: &[u8]) -> Option<usize> {
        match self.look_segment(input) {
            0 => None,
            n => Some(n),
        }
    }

    // userinfo "@"
    //
    // Walks the userinfo run instead of searching for "@" first, so a host
    // without userinfo costs its own length rather than a 256-byte search.
    fn look_userinfo_at(&self, input: &[u8]) -> Option<usize> {
        let table = self.body_classes();
        let mut idx = 0;
        while idx < input.len() && idx < 256 {
            let b = input[idx];
            if b == b'@' {
                return Some(idx + 1);
            }
            if table[b as usize] & USERINFO != 0 {
                idx += 1;
            } else if b == b'%' {
                idx += self.look_pct_encoded(&input[idx..])?;
            } else {
                return None;
            }
        }
        None
    }

    // IP-literal / IPv4address / reg-name
    fn look_host(&self, input: &[u8]) -> Option<usize> {
        if let Some(idx) = self.look_ip_literal(input) {
            // "[::1]x" — an IP-literal glued to further token characters is
            // invalid (only ":" port, path, query, or fragment may follow
            // "]") and would end the match mid-token: reject the candidate.
            if input
                .get(idx)
                .is_some_and(|&b| b.is_ascii_alphanumeric() || b == b'.' || b == b'+' || b == b'-')
            {
                return None;
            }
            return Some(idx);
        }
        if let Some(idx) = self.look_ipv4_address(input) {
            match input.get(idx) {
                // The dotted quad is only a prefix of a longer reg-name
                // ("10.0.0.1.nip.io", "1.2.3.4.5"): parse it as a hostname.
                Some(&b) if b == b'.' || b == b'-' || b == b'_' || b.is_ascii_alphanumeric() => {}
                // Host glued to non-ASCII is IRI garbage: reject.
                Some(&b) if b >= 0x80 => return None,
                _ => return Some(idx),
            }
        }
        self.look_hostname(input)
    }

    // "[" ( IPv6address / IPv6addrz / IPvFuture ) "]"
    fn look_ip_literal(&self, input: &[u8]) -> Option<usize> {
        let mut idx = 0;
        idx += self.look_left_bracket(&input[idx..])?;
        let right_bracket_index = input[idx..].iter().take(64).position(|&b| b == b']')?;
        if right_bracket_index > 0 {
            let end = idx + right_bracket_index;
            let slice = &input[idx..end];
            if self.is_ipv6address(slice) || self.is_ipv6addrz(slice) || self.is_ipvfuture(slice) {
                return Some(end + 1);
            }
        }
        None
    }

    // IPv6addrz = IPv6address "%25" ZoneID (RFC 6874). Leniently, a bare "%"
    // separator is also accepted ("[fe80::1%eth0]" as produced by OS tools).
    fn is_ipv6addrz(&self, input: &[u8]) -> bool {
        let Some(pct) = input.iter().position(|&b| b == b'%') else {
            return false;
        };
        if !self.is_ipv6address(&input[..pct]) {
            return false;
        }
        let mut zone = &input[pct + 1..];
        if zone.starts_with(b"25") && zone.len() > 2 {
            zone = &zone[2..]; // RFC 6874 "%25" delimiter
        }
        !zone.is_empty() && zone.iter().all(|&b| Self::is_unreserved(b))
    }

    // Delegates to the std-exact validator in `crate::ipv6`, which handles
    // embedded IPv4 tails ("::ffff:127.0.0.1", "64:ff9b::192.0.2.33").
    fn is_ipv6address(&self, input: &[u8]) -> bool {
        crate::ipv6::is_valid_ipv6(input)
    }

    // "v" 1*HEXDIG "." 1*( unreserved / sub-delims / ":" )
    fn is_ipvfuture(&self, input: &[u8]) -> bool {
        if input.is_empty() || input[0] != b'v' {
            return false;
        }

        let mut idx = 1;

        // 1*HEXDIG
        let hexdig_start = idx;
        while idx < input.len() && Self::is_hexdig(input[idx]) {
            idx += 1;
        }
        if idx == hexdig_start {
            return false; // Need at least one HEXDIG
        }

        // "."
        if idx >= input.len() || input[idx] != b'.' {
            return false;
        }
        idx += 1;

        // 1*( unreserved / sub-delims / ":" )
        let char_start = idx;
        while idx < input.len() {
            let c = input[idx];
            if Self::is_unreserved(c) || Self::is_sub_delim_strict(c) || c == b':' {
                idx += 1;
            } else {
                break;
            }
        }
        if idx == char_start {
            return false; // Need at least one character after the dot
        }

        idx == input.len()
    }

    #[inline]
    fn is_sub_delim_strict(c: u8) -> bool {
        SUB_DELIMS_STRICT[c as usize]
    }

    // dec-octet "." dec-octet "." dec-octet "." dec-octet
    fn look_ipv4_address(&self, input: &[u8]) -> Option<usize> {
        let mut idx = 0;
        idx += self.look_dec_octet(&input[idx..])?;
        idx += self.look_period(&input[idx..])?;
        idx += self.look_dec_octet(&input[idx..])?;
        idx += self.look_period(&input[idx..])?;
        idx += self.look_dec_octet(&input[idx..])?;
        idx += self.look_period(&input[idx..])?;
        idx += self.look_dec_octet(&input[idx..])?;
        Some(idx)
    }

    // dec-octet     = DIGIT                 ; 0-9
    //               / %x31-39 DIGIT         ; 10-99
    //               / "1" 2DIGIT            ; 100-199
    //               / "2" %x30-34 DIGIT     ; 200-249
    //               / "25" %x30-35          ; 250-255
    fn look_dec_octet(&self, input: &[u8]) -> Option<usize> {
        if input.len() >= 3
            && input[0] == b'2'
            && input[1] == b'5'
            && Self::is_digit_0_to_5(input[2])
        {
            return Some(3);
        }

        if input.len() >= 3
            && input[0] == b'2'
            && Self::is_digit_0_to_4(input[1])
            && Self::is_digit(input[2])
        {
            return Some(3);
        }

        if input.len() >= 3
            && input[0] == b'1'
            && Self::is_digit(input[1])
            && Self::is_digit(input[2])
        {
            return Some(3);
        }

        if input.len() >= 2 && Self::is_digit_1_to_9(input[0]) && Self::is_digit(input[1]) {
            return Some(2);
        }

        if !input.is_empty() && Self::is_digit(input[0]) {
            return Some(1);
        }

        None
    }

    // https://en.wikipedia.org/wiki/Hostname#Restrictions_on_valid_hostnames
    //
    // Rejecting (rather than truncating) oversized labels/hostnames keeps
    // matches from ending mid-token, which would desynchronize the Scanner
    // from slice-based find() restarts.
    fn look_hostname(&self, input: &[u8]) -> Option<usize> {
        const MAX_LABEL: usize = 63; // RFC 1035
        const MAX_HOSTNAME: usize = 253;

        let mut idx = 0;
        loop {
            let run = Self::label_run_len(&input[idx..]);
            if run == 0 {
                break; // only reachable at idx == 0 (possibly-empty host)
            }
            if run > MAX_LABEL {
                return None;
            }
            idx += run;
            // Consume a "." only when another label follows (a trailing dot is
            // sentence punctuation, not part of the host).
            if input.get(idx) == Some(&b'.') && Self::label_run_len(&input[idx + 1..]) > 0 {
                idx += 1;
                continue;
            }
            break;
        }
        if idx > MAX_HOSTNAME {
            return None;
        }
        // A host that stops right before a non-ASCII byte (also right after an
        // unconsumed dot) is the ASCII prefix of an IRI: reject the candidate.
        match input.get(idx) {
            Some(&b) if b >= 0x80 => return None,
            Some(&b'.') if input.get(idx + 1).is_some_and(|&b| b >= 0x80) => return None,
            _ => {}
        }
        Some(idx)
    }

    // Length of the maximal label-character run: [A-Za-z0-9_] first, then also
    // "-". Returns 0 when no label starts here.
    fn label_run_len(input: &[u8]) -> usize {
        let starts = input
            .first()
            .is_some_and(|&b| b.is_ascii_alphanumeric() || b == b'_');
        if !starts {
            return 0;
        }
        // Both modes share the label class.
        let table = &BODY_CLASSES_LAX;
        let mut len = 1;
        while len < input.len() && table[input[len] as usize] & LABEL != 0 {
            len += 1;
        }
        len
    }

    // *DIGIT
    fn look_port(&self, input: &[u8]) -> usize {
        input.iter().take_while(|&&c| Self::is_digit(c)).count()
    }

    fn look_question_mark_query(&self, input: &[u8]) -> Option<usize> {
        let mut idx = 0;
        idx += self.look_question_mark(&input[idx..])?;
        idx += self.look_query(&input[idx..]);
        Some(idx)
    }

    // *( pchar / "/" / "?" )
    fn look_query(&self, input: &[u8]) -> usize {
        self.look_run(input, QUERY)
    }

    fn look_sharp_fragment(&self, input: &[u8]) -> Option<usize> {
        let mut idx = 0;
        idx += self.look_sharp(&input[idx..])?;
        idx += self.look_fragment(&input[idx..]);
        Some(idx)
    }

    // *( pchar / "/" / "?" )
    fn look_fragment(&self, input: &[u8]) -> usize {
        self.look_run(input, QUERY)
    }

    // "%" HEXDIG HEXDIG
    #[inline]
    fn look_pct_encoded(&self, input: &[u8]) -> Option<usize> {
        if input.len() >= 3
            && input[0] == b'%'
            && Self::is_hexdig(input[1])
            && Self::is_hexdig(input[2])
        {
            Some(3)
        } else {
            None
        }
    }

    #[inline]
    fn look_period(&self, input: &[u8]) -> Option<usize> {
        if !input.is_empty() && input[0] == b'.' {
            Some(1)
        } else {
            None
        }
    }

    #[inline]
    fn look_left_bracket(&self, input: &[u8]) -> Option<usize> {
        if !input.is_empty() && input[0] == b'[' {
            Some(1)
        } else {
            None
        }
    }

    #[inline]
    fn look_colon(&self, input: &[u8]) -> Option<usize> {
        if !input.is_empty() && input[0] == b':' {
            Some(1)
        } else {
            None
        }
    }

    #[inline]
    fn look_question_mark(&self, input: &[u8]) -> Option<usize> {
        if !input.is_empty() && input[0] == b'?' {
            Some(1)
        } else {
            None
        }
    }

    #[inline]
    fn look_sharp(&self, input: &[u8]) -> Option<usize> {
        if !input.is_empty() && input[0] == b'#' {
            Some(1)
        } else {
            None
        }
    }

    #[inline]
    fn look_slash(&self, input: &[u8]) -> Option<usize> {
        if !input.is_empty() && input[0] == b'/' {
            Some(1)
        } else {
            None
        }
    }

    #[inline]
    fn look_slash_slash(&self, input: &[u8]) -> Option<usize> {
        if input.len() >= 2 && input[0] == b'/' && input[1] == b'/' {
            Some(2)
        } else {
            None
        }
    }

    // ALPHA / DIGIT / "-" / "." / "_" / "~"
    #[inline]
    fn is_unreserved(c: u8) -> bool {
        c.is_ascii_alphanumeric() || c == b'-' || c == b'.' || c == b'_' || c == b'~'
    }

    #[inline]
    fn is_alpha(c: u8) -> bool {
        c.is_ascii_alphabetic()
    }

    #[inline]
    fn is_digit(c: u8) -> bool {
        c.is_ascii_digit()
    }

    #[inline]
    fn is_digit_1_to_9(c: u8) -> bool {
        (b'1'..=b'9').contains(&c)
    }

    #[inline]
    fn is_digit_0_to_4(c: u8) -> bool {
        (b'0'..=b'4').contains(&c)
    }

    #[inline]
    fn is_digit_0_to_5(c: u8) -> bool {
        (b'0'..=b'5').contains(&c)
    }

    #[inline]
    fn is_hexdig(c: u8) -> bool {
        c.is_ascii_hexdigit()
    }
}

#[cfg(test)]
#[allow(clippy::bool_assert_comparison)]
#[allow(clippy::useless_vec)]
#[allow(clippy::field_reassign_with_default)]
mod tests {
    use super::*;

    #[test]
    fn is_ipv6address_should_identify_valid_ipv6s() {
        let finder = URI::default();
        for input in [
            "::",
            "::1",
            "1::",
            "1:2:3:4:5:6:7:8",
            "1:2:3:4:5:6::7",
            "1:2:3:4:5:6:127.0.0.1",
            "1::127.0.0.1",
        ] {
            assert_eq!(true, finder.is_ipv6address(input.as_bytes()), "{}", input);
        }
    }

    #[test]
    fn is_ipv6address_should_identify_invalid_ipv6s() {
        let finder = URI::default();
        for input in vec![
            " ",
            " ::",
            ":: ",
            " :: ",
            ":::",
            "::1::",
            ":1:",
            "1:2:3:4:5:6:7:8:9",
            "1:2:3:4:5:6:7:127.0.0.1",
            "1:2:3:4:5:6::7:8",
            "1:2:3:4:5:6::127.0.0.1",
            "1:127.0.0.1::",
        ] {
            assert_eq!(false, finder.is_ipv6address(input.as_bytes()), "{}", input);
        }
    }

    #[test]
    fn look_path_abempty_should_mirror_the_len_of_valid_inputs() {
        let finder = URI::default();
        for input in vec![
            "",
            "/",
            "//",
            "///",
            "/foo/bar",
            "/rfc/rfc1808.txt",
            "/with/trailing/",
        ] {
            assert_eq!(
                input.len(),
                finder.look_path_abempty(input.as_bytes()),
                "{}",
                input
            );
        }
    }

    #[test]
    fn look_path_abempty_should_skip_invalid_inputs() {
        let finder = URI::default();
        for input in vec!["foobar"] {
            assert_eq!(0, finder.look_path_abempty(input.as_bytes()), "{}", input);
        }
    }

    #[test]
    fn it_should_mirror_valid_uris() {
        let finder = URI::default();
        for input in vec![
            // basic
            "http://localhost",
            // userinfo
            "http://foobar:@localhost",
            "http://foobar:baz@localhost",
            // port
            "http://foobar:@localhost:8080",
            // path
            "http://localhost/lorem",
            // query
            "http://foobar:@localhost:8080?a=b",
            // fragment
            "http://foobar:@localhost:8080#",
            "http://foobar:@localhost:8080?#",
            "http://foobar:@localhost:8080?a=b#",
            "http://foobar:@localhost:8080?a=b#c=d",
            // meh
            "http://:@localhost:/?#",
            // ipv4
            "http://127.0.0.0",
            "http://127.0.0.10",
            "http://127.0.0.100",
            "http://127.0.0.200",
            "http://127.0.0.250",
            "http://192.0.2.235",
            // ipv6
            "http://[::]",
            "http://[::1]",
            "http://[2001:db8::1]",
            "http://[2001:0db8::0001]",
            "http://[2001:0db8:85a3:0000:0000:8a2e:0370:7334]",
            "http://[::ffff:192.0.2.128]",
            "http://[::ffff:c000:0280]",
            // rfc examples
            "file:///etc/hosts",
            "http://localhost/",
            "mailto:fred@example.com",
            "foo://info.example.com?fred",
            "ftp://ftp.is.co.za/rfc/rfc1808.txt",
            "http://www.ietf.org/rfc/rfc2396.txt",
            "ldap://[2001:db8::7]/c=GB?objectClass?one",
            "mailto:John.Doe@example.com",
            "news:comp.infosystems.www.servers.unix",
            "tel:+1-816-555-1212",
            "telnet://192.0.2.16:80/",
            "urn:oasis:names:specification:docbook:dtd:xml:4.1.2",
        ] {
            for i in vec![
                input.to_owned(),
                format!(" {} ", input),
                format!("<{}>", input),
                format!("[{}]", input),
                format!("<a href=\"{}\">link</a>", input),
                format!("{{{}}}", input),
                format!("\"{}\"", input),
                format!("[link]({})", input),
                format!("'{}'", input),
            ] {
                assert_eq!(Some(input), finder.find(&i).map(|r| &i[r]), "{}", input);
            }
        }
    }

    #[test]
    fn it_should_properly_behave_in_strict_mode() {
        let mut finder = URI::default();
        finder.strict = true;
        for &input in &[
            "http://localhost/)",
            "http://localhost/'",
            // Trailing empty port / empty query / "!" are trimmed in lax mode
            // but strictly valid per RFC 3986.
            "http://foobar:@localhost:",
            "http://foobar:@localhost:8080?",
            "data:,Hello%2C%20World!",
        ] {
            assert_eq!(Some(input), finder.find(input).map(|r| &input[r]));
        }
    }

    #[test]
    fn it_should_ignore_invalid_uris() {
        let finder = URI::default();
        for input in vec![
            // some protocols require a host
            "ftp:///test",
            "http:///test",
            "https:///test",
        ] {
            assert_eq!(None, finder.find(input), "{}", input);
        }
    }

    #[test]
    fn is_ipvfuture_should_identify_valid_ipvfutures() {
        let finder = URI::default();
        for input in vec![
            "v1.test",
            "vFF.a",
            "v1.fe80",
            "v1.a:b:c",
            "vABCDEF.test",
            "v1.unreserved-chars_here~",
            "v1.sub!delims$and&more",
        ] {
            assert_eq!(true, finder.is_ipvfuture(input.as_bytes()), "{}", input);
        }
    }

    #[test]
    fn is_ipvfuture_should_identify_invalid_ipvfutures() {
        let finder = URI::default();
        for input in vec![
            "", "v", "v1", "v1.", "v.", "v.test", "1.test",
            "vGG.test", // G is not a valid hex digit
        ] {
            assert_eq!(false, finder.is_ipvfuture(input.as_bytes()), "{}", input);
        }
    }

    #[test]
    fn it_should_mirror_valid_ipvfuture_uris() {
        let finder = URI::default();
        for input in vec![
            "http://[v1.test]/path",
            "http://[vFF.fe80]/",
            "http://[v1.a:b:c]",
            "http://[v1.test]:8080/path",
        ] {
            assert_eq!(
                Some(input),
                finder.find(input).map(|r| &input[r]),
                "{}",
                input
            );
        }
    }

    #[test]
    fn it_should_mirror_data_uris() {
        let finder = URI::default();
        for input in vec![
            "data:text/plain;base64,SGVsbG8=",
            "data:image/png;base64,iVBORw0KGgo=",
            "data:,Hello%2C%20World",
            "data:text/html,%3Ch1%3EHello%3C%2Fh1%3E",
        ] {
            assert_eq!(
                Some(input),
                finder.find(input).map(|r| &input[r]),
                "{}",
                input
            );
        }
    }

    #[test]
    fn it_should_mirror_mailto_uris() {
        let finder = URI::default();
        for input in vec![
            "mailto:user@example.com",
            "mailto:user@example.com?subject=Hello&body=World",
            "mailto:user@example.com,other@example.com",
        ] {
            assert_eq!(
                Some(input),
                finder.find(input).map(|r| &input[r]),
                "{}",
                input
            );
        }
    }

    #[test]
    fn it_should_mirror_tel_uris() {
        let finder = URI::default();
        for input in vec![
            "tel:+1-816-555-1212",
            "tel:+1-816-555-1212;ext=1234",
            "tel:911",
        ] {
            assert_eq!(
                Some(input),
                finder.find(input).map(|r| &input[r]),
                "{}",
                input
            );
        }
    }

    #[test]
    fn it_should_mirror_uris_with_percent_encoding() {
        let finder = URI::default();
        for input in vec![
            "http://example.com/path%20with%20spaces",
            "http://example.com/path?q=%E2%9C%93",
            "http://user%40name:pass%23word@example.com",
        ] {
            assert_eq!(
                Some(input),
                finder.find(input).map(|r| &input[r]),
                "{}",
                input
            );
        }
    }

    #[test]
    fn it_should_mirror_uris_with_fragments() {
        let finder = URI::default();
        for input in vec![
            "http://example.com#section",
            "http://example.com/page#",
            "http://example.com?query#fragment",
        ] {
            assert_eq!(
                Some(input),
                finder.find(input).map(|r| &input[r]),
                "{}",
                input
            );
        }
    }

    #[test]
    fn it_should_mirror_uris_with_empty_paths() {
        let finder = URI::default();
        for input in vec!["http://example.com?query", "http://example.com#fragment"] {
            assert_eq!(
                Some(input),
                finder.find(input).map(|r| &input[r]),
                "{}",
                input
            );
        }
    }

    #[test]
    fn it_should_mirror_uris_with_multiple_slashes() {
        let finder = URI::default();
        for input in vec![
            "http://example.com//path",
            "http://example.com//path///to////resource",
        ] {
            assert_eq!(
                Some(input),
                finder.find(input).map(|r| &input[r]),
                "{}",
                input
            );
        }
    }

    #[test]
    fn it_should_mirror_ipv4_mapped_ipv6_uris() {
        let finder = URI::default();
        for input in vec![
            "http://[::ffff:192.168.1.1]",
            "http://[::ffff:127.0.0.1]:8080/path",
        ] {
            assert_eq!(
                Some(input),
                finder.find(input).map(|r| &input[r]),
                "{}",
                input
            );
        }
    }

    #[test]
    fn it_should_mirror_punycode_domains() {
        let finder = URI::default();
        for input in vec!["http://xn--n3h.com", "http://xn--nxasmq5b.com"] {
            assert_eq!(
                Some(input),
                finder.find(input).map(|r| &input[r]),
                "{}",
                input
            );
        }
    }

    #[test]
    fn it_should_mirror_hostnames_with_underscores() {
        let finder = URI::default();
        for input in vec!["http://my_server.local", "http://_dmarc.example.com"] {
            assert_eq!(
                Some(input),
                finder.find(input).map(|r| &input[r]),
                "{}",
                input
            );
        }
    }

    #[test]
    fn it_should_mirror_single_label_hostnames() {
        let finder = URI::default();
        for input in vec![
            "http://localhost",
            "http://intranet",
            "http://localhost:8080",
        ] {
            assert_eq!(
                Some(input),
                finder.find(input).map(|r| &input[r]),
                "{}",
                input
            );
        }
    }

    // ============================================================================
    // Edge case tests
    // ============================================================================

    #[test]
    fn it_should_handle_empty_string() {
        let finder = URI::default();
        assert_eq!(None, finder.find(""));
    }

    #[test]
    fn it_should_handle_string_without_uris() {
        let finder = URI::default();
        // Note: URIs require scheme:... where scheme starts with ALPHA
        // So inputs without colons or with only non-alpha before colon won't match
        for input in vec![
            "hello world",
            "no urls here",
            "just some text",
            "12345",      // no colon
            "   ",        // no colon
            "123:456",    // scheme must start with alpha
            ":no-scheme", // colon at start
        ] {
            assert_eq!(None, finder.find(input), "{}", input);
        }
    }

    #[test]
    fn it_should_handle_very_long_uris() {
        let finder = URI::default();

        // Long path
        let long_path = format!("http://example.com/{}", "a".repeat(2000));
        assert_eq!(
            Some(long_path.as_str()),
            finder.find(&long_path).map(|r| &long_path[r])
        );

        // Long query
        let long_query = format!("http://example.com?q={}", "b".repeat(2000));
        assert_eq!(
            Some(long_query.as_str()),
            finder.find(&long_query).map(|r| &long_query[r])
        );

        // Long fragment
        let long_fragment = format!("http://example.com#{}", "c".repeat(2000));
        assert_eq!(
            Some(long_fragment.as_str()),
            finder.find(&long_fragment).map(|r| &long_fragment[r])
        );
    }

    #[test]
    fn it_should_handle_malformed_percent_encoding() {
        let finder = URI::default();

        // Valid percent encoding
        assert!(finder.find("http://example.com/%20").is_some());
        assert!(finder.find("http://example.com/%2F").is_some());

        // Invalid hex digits - should stop before invalid encoding
        let input = "http://example.com/path%GG";
        let result = finder.find(input).map(|r| &input[r]);
        assert_eq!(Some("http://example.com/path"), result);

        let input2 = "http://example.com/path%ZZ";
        let result2 = finder.find(input2).map(|r| &input2[r]);
        assert_eq!(Some("http://example.com/path"), result2);
    }

    #[test]
    fn it_should_handle_incomplete_percent_encoding() {
        let finder = URI::default();

        // Single % at end
        let input = "http://example.com/path%";
        let result = finder.find(input).map(|r| &input[r]);
        assert_eq!(Some("http://example.com/path"), result);

        // % with only one hex digit
        let input2 = "http://example.com/path%2";
        let result2 = finder.find(input2).map(|r| &input2[r]);
        assert_eq!(Some("http://example.com/path"), result2);
    }

    #[test]
    fn it_should_handle_unicode_in_hostnames() {
        let finder = URI::default();

        // Punycode domains (IDN)
        for input in vec![
            "http://xn--n3h.com",        // Unicode domain encoded as punycode
            "http://xn--nxasmq5b.com",   // Another punycode domain
            "http://xn--80ak6aa92e.com", // Yet another
        ] {
            assert!(finder.find(input).is_some(), "{}", input);
        }
    }

    #[test]
    fn it_should_handle_edge_case_ports() {
        let finder = URI::default();

        // Empty port
        assert!(finder.find("http://example.com:").is_some());

        // Port 0
        assert!(finder.find("http://example.com:0").is_some());

        // Very large port number (technically invalid but should parse)
        assert!(finder.find("http://example.com:99999").is_some());
    }

    #[test]
    fn it_should_handle_edge_case_userinfo() {
        let finder = URI::default();

        // Empty userinfo with @
        assert!(finder.find("http://@example.com").is_some());

        // Only username
        assert!(finder.find("http://user@example.com").is_some());

        // Username and empty password
        assert!(finder.find("http://user:@example.com").is_some());

        // Empty username and password
        assert!(finder.find("http://:pass@example.com").is_some());

        // Special characters in userinfo (percent-encoded)
        assert!(finder.find("http://user%40name@example.com").is_some());
    }

    #[test]
    fn it_should_handle_consecutive_special_chars() {
        let finder = URI::default();

        // Multiple query params
        assert!(finder.find("http://example.com?a=1&b=2&c=3").is_some());

        // Fragment parsing stops at second # (RFC 3986 fragment is *( pchar / "/" / "?" ))
        let input = "http://example.com#frag#ment";
        // The # character is not valid in a fragment, so parsing stops at #frag
        assert_eq!(
            Some("http://example.com#frag"),
            finder.find(input).map(|r| &input[r])
        );

        // Query then fragment
        assert!(finder.find("http://example.com?query#fragment").is_some());
    }

    #[test]
    fn it_should_handle_scheme_edge_cases() {
        let finder = URI::default();

        // Scheme with numbers
        assert!(finder.find("h2c://example.com").is_some());

        // Scheme with plus
        assert!(finder.find("coap+tcp://example.com").is_some());

        // Scheme with dots
        assert!(finder.find("x.y.z://example.com").is_some());

        // Scheme with hyphens
        assert!(finder.find("my-scheme://example.com").is_some());

        // Single letter scheme
        assert!(finder.find("x://example.com").is_some());
    }

    #[test]
    fn it_should_handle_ipv4_edge_cases() {
        let finder = URI::default();

        // Boundary values
        assert!(finder.find("http://0.0.0.0").is_some());
        assert!(finder.find("http://255.255.255.255").is_some());

        // Invalid IP (256) - should still find partial
        let input = "http://256.0.0.1";
        assert!(finder.find(input).is_some()); // Finds as hostname

        // Leading zeros (valid but unusual)
        assert!(finder.find("http://192.168.001.001").is_some());
    }

    #[test]
    fn it_should_handle_multiple_uris_in_text() {
        let finder = URI::default();

        let text = "Visit http://first.com and https://second.com today";
        let result = finder.find(text);
        assert!(result.is_some());
        assert_eq!("http://first.com", &text[result.unwrap()]);
    }

    #[test]
    fn it_should_handle_uri_at_string_boundaries() {
        let finder = URI::default();

        // URI at start
        let input1 = "http://example.com is a URL";
        assert_eq!(
            Some("http://example.com"),
            finder.find(input1).map(|r| &input1[r])
        );

        // URI at end
        let input2 = "Visit http://example.com";
        assert_eq!(
            Some("http://example.com"),
            finder.find(input2).map(|r| &input2[r])
        );

        // URI alone
        let input3 = "http://example.com";
        assert_eq!(
            Some("http://example.com"),
            finder.find(input3).map(|r| &input3[r])
        );
    }

    #[test]
    fn it_should_filter_by_scheme() {
        let mut finder = URI::default();
        finder.add_scheme("https");

        // Should match https
        let input1 = "https://secure.com";
        assert_eq!(Some(input1), finder.find(input1).map(|r| &input1[r]));

        // Should skip http, find nothing
        let input2 = "http://insecure.com";
        assert_eq!(None, finder.find(input2));

        // Should skip http and find https
        let input3 = "http://first.com https://second.com";
        assert_eq!(
            Some("https://second.com"),
            finder.find(input3).map(|r| &input3[r])
        );
    }

    #[test]
    fn it_should_handle_scheme_case_insensitivity() {
        let mut finder = URI::default();
        finder.add_scheme("HTTP");

        // Should match lowercase http
        let input = "http://example.com";
        assert_eq!(Some(input), finder.find(input).map(|r| &input[r]));

        // Should also match uppercase input schemes
        let input = "HTTP://example.com";
        assert_eq!(Some(input), finder.find(input).map(|r| &input[r]));
    }

    #[test]
    fn uppercase_http_scheme_obeys_host_rules() {
        let finder = URI::default();
        assert_eq!(None, finder.find("HTTP:///missing-host"));
        assert_eq!(None, finder.find("HTTPS:///missing-host"));
    }

    // --- Regression: sorted Vec scheme dedup ---

    #[test]
    fn add_scheme_deduplicates() {
        let mut finder = URI::default();
        finder.add_scheme("http");
        finder.add_scheme("http");
        finder.add_scheme("HTTP");
        assert_eq!(finder.schemes.len(), 1);
    }

    #[test]
    fn add_scheme_multiple_sorted() {
        let mut finder = URI::default();
        finder.add_scheme("https");
        finder.add_scheme("ftp");
        finder.add_scheme("http");
        assert_eq!(finder.schemes, vec!["ftp", "http", "https"]);
    }

    // --- Regression: look_pchar branch order ---

    #[test]
    fn look_pchar_unreserved_chars() {
        let finder = URI::default();
        for input in [
            "http://example.com/path-with-dashes_and_underscores.and.dots~tilde",
            "http://example.com/ABCDEFGHIJKLMNOPQRSTUVWXYZ",
            "http://example.com/abcdefghijklmnopqrstuvwxyz",
            "http://example.com/0123456789",
        ] {
            assert_eq!(
                Some(input),
                finder.find(input).map(|r| &input[r]),
                "{}",
                input
            );
        }
    }

    #[test]
    fn look_pchar_pct_encoded() {
        let finder = URI::default();
        let input = "http://example.com/%20%2F%3A";
        assert_eq!(Some(input), finder.find(input).map(|r| &input[r]));
    }

    #[test]
    fn look_pchar_sub_delims() {
        let finder = URI::default();
        let input = "http://example.com/path!$&(*+,;=";
        assert_eq!(Some(input), finder.find(input).map(|r| &input[r]));
    }

    // --- Regression: rlook_scheme cap ---

    #[test]
    fn rlook_scheme_very_long_prefix() {
        let finder = URI::default();
        let long_prefix = " ".repeat(1000);
        let input = format!("{}http://example.com", long_prefix);
        assert_eq!(
            Some("http://example.com"),
            finder.find(&input).map(|r| &input[r])
        );
    }

    #[test]
    fn rlook_scheme_just_within_cap() {
        let finder = URI::default();
        let scheme = "a".repeat(30);
        let input = format!("{}://host", scheme);
        assert_eq!(Some(input.as_str()), finder.find(&input).map(|r| &input[r]));
    }

    #[test]
    fn registered_schemes_should_fit_the_scheme_lookback() {
        for scheme in crate::iana::URI_SCHEMES.iter() {
            assert!(scheme.len() <= MAX_SCHEME_LEN, "{scheme}");
        }
    }

    #[test]
    fn find_should_keep_long_registered_opaque_uris() {
        let finder = URI::default();
        let input = "open microsoft.windows.camera.multipicker:photo now";
        assert_eq!(
            Some("microsoft.windows.camera.multipicker:photo"),
            finder.find(input).map(|r| &input[r])
        );
    }

    #[test]
    fn rlook_scheme_exceeds_cap() {
        let finder = URI::default();
        let scheme = "a".repeat(MAX_SCHEME_LEN + 8);
        let input = format!("{}://host", scheme);
        // Scheme longer than MAX_SCHEME_LEN gets truncated, but the URI
        // is still found with a shorter scheme prefix
        let result = finder.find(&input);
        assert!(result.is_some());
    }

    // --- Regression: sub-delim lookup table ---

    #[test]
    fn sub_delim_strict_vs_lax() {
        let strict = {
            let mut f = URI::default();
            f.strict = true;
            f
        };
        let lax = URI::default();

        let with_apos = "http://example.com/it's";
        assert_eq!(
            Some("http://example.com/it's"),
            strict.find(with_apos).map(|r| &with_apos[r])
        );
        assert_eq!(
            Some("http://example.com/it"),
            lax.find(with_apos).map(|r| &with_apos[r])
        );

        let with_paren = "http://example.com/path)";
        assert_eq!(
            Some("http://example.com/path)"),
            strict.find(with_paren).map(|r| &with_paren[r])
        );
        assert_eq!(
            Some("http://example.com/path"),
            lax.find(with_paren).map(|r| &with_paren[r])
        );
    }
}