epics-base-rs 0.18.2

use crate::error::{CaError, CaResult};
use crate::server::record::{FieldDesc, ProcessOutcome, Record};
use crate::types::{DbFieldType, EpicsValue};

// printf record (EPICS 7).
// Evaluates FMT as a printf format string with up to 10 inputs (INP0-INP9, values A-J).
// Each format specifier in FMT consumes the next input in order. A `*`
// (variable width/precision) also consumes one input. VAL holds the
// resulting string (capped by SIZV).
//
// C `printfRecord.c::doPrintf` reads each input link with the DBR type
// implied by the conversion + length modifier: `%s`/`%ls` read a
// string, the numeric conversions read a number. The Rust framework
// pre-fetches every INPn link into the matching value field A..J; we
// therefore store the raw `EpicsValue` per slot so a `%s` conversion
// can recover the string content (H-6) instead of stringifying a
// coerced f64.
pub struct PrintfRecord {
    pub val: String,
    pub sizv: u16,
    pub fmt: String,
    /// INP0-INP9: input link strings.
    pub inp_links: [String; 10],
    /// A-J: current values from the input links, kept in their native
    /// type. `%s` reads the string form, numeric conversions read the
    /// numeric form.
    pub vals: [EpicsValue; 10],
}

impl Default for PrintfRecord {
    fn default() -> Self {
        Self {
            val: String::new(),
            sizv: 256,
            fmt: String::new(),
            inp_links: Default::default(),
            vals: std::array::from_fn(|_| EpicsValue::Double(0.0)),
        }
    }
}

/// One parsed printf conversion directive.
struct Directive {
    /// Width; `None` when given as `*` (read from the next input).
    width: Option<usize>,
    star_width: bool,
    /// Precision; `None` when absent, `Some(*)` flag handled separately.
    precision: Option<usize>,
    star_prec: bool,
    left_align: bool,
    zero_pad: bool,
    alt_form: bool, // '#'
    /// Final conversion character.
    conv: u8,
    /// `l`/`ll` long modifier present (selects `%ls` long string).
    long: bool,
    bad: bool,
}

impl PrintfRecord {
    /// Stringify an input value for the `%s` / `%ls` conversion.
    /// Mirrors C reading the link as `DBR_STRING` / `DBR_CHAR`.
    fn val_as_string(v: &EpicsValue) -> String {
        match v {
            EpicsValue::String(s) => s.clone(),
            EpicsValue::CharArray(bytes) => {
                let end = bytes.iter().position(|&b| b == 0).unwrap_or(bytes.len());
                String::from_utf8_lossy(&bytes[..end]).into_owned()
            }
            EpicsValue::Double(d) => format!("{d}"),
            EpicsValue::Float(f) => format!("{f}"),
            EpicsValue::Long(n) => format!("{n}"),
            EpicsValue::Short(n) => format!("{n}"),
            EpicsValue::Int64(n) => format!("{n}"),
            EpicsValue::Char(c) => format!("{c}"),
            EpicsValue::Enum(e) => format!("{e}"),
            other => format!("{other:?}"),
        }
    }

    fn val_as_f64(v: &EpicsValue) -> f64 {
        v.to_f64().unwrap_or(0.0)
    }

    /// Parse one `%...` directive starting at `bytes[i]` (which is `%`).
    /// Returns the directive and the index just past the conversion
    /// char. Consumes `*` width/precision values from `star_idx`.
    fn parse_directive(bytes: &[u8], mut i: usize) -> (Directive, usize) {
        let mut d = Directive {
            width: None,
            star_width: false,
            precision: None,
            star_prec: false,
            left_align: false,
            zero_pad: false,
            alt_form: false,
            conv: b's',
            long: false,
            bad: false,
        };
        i += 1; // skip '%'
        // Flags.
        loop {
            match bytes.get(i) {
                Some(b'-') => d.left_align = true,
                Some(b'+') | Some(b' ') => {}
                Some(b'#') => d.alt_form = true,
                Some(b'0') => d.zero_pad = true,
                _ => break,
            }
            i += 1;
        }
        // Width.
        if bytes.get(i) == Some(&b'*') {
            d.star_width = true;
            i += 1;
        } else {
            let mut w = 0usize;
            let mut any = false;
            while let Some(c) = bytes.get(i) {
                if c.is_ascii_digit() {
                    w = w * 10 + (c - b'0') as usize;
                    any = true;
                    i += 1;
                } else {
                    break;
                }
            }
            if any {
                d.width = Some(w);
            }
        }
        // Precision.
        if bytes.get(i) == Some(&b'.') {
            i += 1;
            if bytes.get(i) == Some(&b'*') {
                d.star_prec = true;
                i += 1;
            } else {
                let mut p = 0usize;
                while let Some(c) = bytes.get(i) {
                    if c.is_ascii_digit() {
                        p = p * 10 + (c - b'0') as usize;
                        i += 1;
                    } else {
                        break;
                    }
                }
                d.precision = Some(p);
            }
        }
        // Length modifiers: h, hh, l, ll.
        loop {
            match bytes.get(i) {
                Some(b'h') => {
                    i += 1;
                }
                Some(b'l') => {
                    d.long = true;
                    i += 1;
                }
                _ => break,
            }
        }
        // Conversion character.
        match bytes.get(i) {
            Some(&c) if b"diouxXeEfFgGcs".contains(&c) => {
                d.conv = c;
                i += 1;
            }
            Some(_) => {
                d.bad = true;
                i += 1;
            }
            None => {
                d.bad = true;
            }
        }
        (d, i)
    }

    fn apply_fmt(&self) -> String {
        let mut result = String::new();
        let bytes = self.fmt.as_bytes();
        let mut i = 0;
        let mut inp_idx = 0usize;

        // Fetch the next input value, advancing the cursor.
        let take = |idx: &mut usize| -> Option<&EpicsValue> {
            if *idx < 10 {
                let v = &self.vals[*idx];
                *idx += 1;
                Some(v)
            } else {
                *idx += 1;
                None
            }
        };

        while i < bytes.len() {
            if bytes[i] != b'%' {
                result.push(bytes[i] as char);
                i += 1;
                continue;
            }
            // %% escape.
            if bytes.get(i + 1) == Some(&b'%') {
                result.push('%');
                i += 2;
                continue;
            }
            let (d, next) = Self::parse_directive(bytes, i);
            i = next;
            if d.bad {
                // Bad format directive — C copies the directive text.
                continue;
            }

            // Resolve `*` width / precision from the next input(s).
            let width = if d.star_width {
                take(&mut inp_idx)
                    .map(|v| Self::val_as_f64(v) as i64)
                    .unwrap_or(0)
            } else {
                d.width.unwrap_or(0) as i64
            };
            let precision = if d.star_prec {
                take(&mut inp_idx)
                    .map(|v| Self::val_as_f64(v) as i64)
                    .unwrap_or(0)
                    .max(0) as usize
            } else {
                d.precision.unwrap_or(usize::MAX)
            };
            let (width, left_align) = if width < 0 {
                ((-width) as usize, true)
            } else {
                (width as usize, d.left_align)
            };

            let arg = take(&mut inp_idx);
            let conv_prec = if precision == usize::MAX {
                6
            } else {
                precision
            };

            let substituted = match d.conv {
                b'd' | b'i' => {
                    let v = arg.map(Self::val_as_f64).unwrap_or(0.0);
                    pad_string(format!("{}", v as i64), width, left_align, d.zero_pad)
                }
                b'u' => {
                    let v = arg.map(Self::val_as_f64).unwrap_or(0.0);
                    pad_string(
                        format!("{}", v as i64 as u64),
                        width,
                        left_align,
                        d.zero_pad,
                    )
                }
                b'o' => {
                    let v = arg.map(Self::val_as_f64).unwrap_or(0.0) as i64 as u64;
                    let s = if d.alt_form && v != 0 {
                        format!("0{v:o}")
                    } else {
                        format!("{v:o}")
                    };
                    pad_string(s, width, left_align, d.zero_pad)
                }
                b'x' => {
                    let v = arg.map(Self::val_as_f64).unwrap_or(0.0) as i64 as u64;
                    let s = if d.alt_form && v != 0 {
                        format!("0x{v:x}")
                    } else {
                        format!("{v:x}")
                    };
                    pad_string(s, width, left_align, d.zero_pad)
                }
                b'X' => {
                    let v = arg.map(Self::val_as_f64).unwrap_or(0.0) as i64 as u64;
                    let s = if d.alt_form && v != 0 {
                        format!("0X{v:X}")
                    } else {
                        format!("{v:X}")
                    };
                    pad_string(s, width, left_align, d.zero_pad)
                }
                b'e' | b'E' | b'f' | b'F' | b'g' | b'G' => {
                    let v = arg.map(Self::val_as_f64).unwrap_or(0.0);
                    let s = format_float_conv(d.conv, v, conv_prec, d.alt_form);
                    pad_string(s, width, left_align, d.zero_pad)
                }
                b'c' => {
                    // %c: the input value as a single character (C reads
                    // DBR_CHAR). Numeric value → its code point.
                    let ch = match arg {
                        Some(EpicsValue::String(s)) => s.chars().next().unwrap_or(' '),
                        Some(v) => {
                            let code = Self::val_as_f64(v) as u32;
                            char::from_u32(code).unwrap_or('\u{0}')
                        }
                        None => '\u{0}',
                    };
                    pad_string(ch.to_string(), width, left_align, false)
                }
                b's' => {
                    // %s / %ls: print the link's STRING content (H-6).
                    let mut s = arg.map(Self::val_as_string).unwrap_or_default();
                    // Precision caps the number of characters printed.
                    if precision != usize::MAX && s.chars().count() > precision {
                        s = s.chars().take(precision).collect();
                    }
                    pad_string(s, width, left_align, false)
                }
                _ => String::new(),
            };
            result.push_str(&substituted);
        }

        let max = (self.sizv as usize).saturating_sub(1);
        if result.len() > max {
            // Truncate on a UTF-8 boundary.
            let trunc = (0..=max)
                .rev()
                .find(|&n| result.is_char_boundary(n))
                .unwrap_or(0);
            result.truncate(trunc);
        }
        result
    }

    fn inp_index(name: &str) -> Option<usize> {
        // INP0-INP9
        let bytes = name.as_bytes();
        if bytes.len() == 4 && &bytes[0..3] == b"INP" {
            let digit = bytes[3];
            if digit.is_ascii_digit() {
                return Some((digit - b'0') as usize);
            }
        }
        None
    }

    fn val_index(name: &str) -> Option<usize> {
        // A-J
        if name.len() == 1 {
            let c = name.as_bytes()[0];
            if (b'A'..=b'J').contains(&c) {
                return Some((c - b'A') as usize);
            }
        }
        None
    }
}

// Apply width padding. Handles left-align, right-align, and zero-fill.
// For zero-fill on signed values the sign is placed before the zeros.
fn pad_string(s: String, width: usize, left_align: bool, zero_pad: bool) -> String {
    if width <= s.chars().count() {
        return s;
    }
    if left_align {
        format!("{s:<width$}")
    } else if zero_pad {
        if s.starts_with('-') || s.starts_with('+') {
            format!("{}{:0>width$}", &s[..1], &s[1..], width = width - 1)
        } else {
            format!("{s:0>width$}")
        }
    } else {
        format!("{s:>width$}")
    }
}

fn format_float_conv(conv: u8, val: f64, prec: usize, alt_form: bool) -> String {
    match conv {
        b'e' => format!("{val:.prec$e}"),
        b'E' => format!("{val:.prec$E}"),
        b'f' | b'F' => format!("{val:.prec$}"),
        b'g' => format_g_val(val, prec, false, alt_form),
        b'G' => format_g_val(val, prec, true, alt_form),
        _ => format!("{val:.prec$}"),
    }
}

fn format_g_val(val: f64, prec: usize, upper: bool, alt_form: bool) -> String {
    if val == 0.0 {
        // libc `%g` of 0.0 is "0"; `%#g` keeps trailing zeros.
        if alt_form {
            let p = if prec == 0 { 1 } else { prec };
            let decimals = p.saturating_sub(1);
            return format!("{:.*}", decimals, 0.0);
        }
        return "0".to_string();
    }
    let p = if prec == 0 { 1 } else { prec };
    let exp = val.abs().log10().floor() as i32;

    if exp < -4 || exp >= p as i32 {
        let sig_prec = p.saturating_sub(1);
        let raw = if upper {
            format!("{val:.sig_prec$E}")
        } else {
            format!("{val:.sig_prec$e}")
        };
        if alt_form {
            raw
        } else {
            strip_trailing_zeros_sci(&raw, upper)
        }
    } else {
        let decimal_places = (p as i32 - 1 - exp).max(0) as usize;
        let raw = format!("{val:.decimal_places$}");
        if alt_form {
            raw
        } else if raw.contains('.') {
            raw.trim_end_matches('0').trim_end_matches('.').to_string()
        } else {
            raw
        }
    }
}

fn strip_trailing_zeros_sci(s: &str, upper: bool) -> String {
    let sep = if upper { 'E' } else { 'e' };
    if let Some(pos) = s.find(sep) {
        let mantissa = &s[..pos];
        let exp_part = &s[pos..];
        let trimmed = if mantissa.contains('.') {
            mantissa.trim_end_matches('0').trim_end_matches('.')
        } else {
            mantissa
        };
        format!("{trimmed}{exp_part}")
    } else {
        s.to_string()
    }
}

static PRINTF_FIELDS: &[FieldDesc] = &[
    FieldDesc {
        name: "VAL",
        dbf_type: DbFieldType::Char,
        read_only: true,
    },
    FieldDesc {
        name: "SIZV",
        dbf_type: DbFieldType::Short,
        read_only: false,
    },
    FieldDesc {
        name: "FMT",
        dbf_type: DbFieldType::String,
        read_only: false,
    },
    FieldDesc {
        name: "INP0",
        dbf_type: DbFieldType::String,
        read_only: false,
    },
    FieldDesc {
        name: "INP1",
        dbf_type: DbFieldType::String,
        read_only: false,
    },
    FieldDesc {
        name: "INP2",
        dbf_type: DbFieldType::String,
        read_only: false,
    },
    FieldDesc {
        name: "INP3",
        dbf_type: DbFieldType::String,
        read_only: false,
    },
    FieldDesc {
        name: "INP4",
        dbf_type: DbFieldType::String,
        read_only: false,
    },
    FieldDesc {
        name: "INP5",
        dbf_type: DbFieldType::String,
        read_only: false,
    },
    FieldDesc {
        name: "INP6",
        dbf_type: DbFieldType::String,
        read_only: false,
    },
    FieldDesc {
        name: "INP7",
        dbf_type: DbFieldType::String,
        read_only: false,
    },
    FieldDesc {
        name: "INP8",
        dbf_type: DbFieldType::String,
        read_only: false,
    },
    FieldDesc {
        name: "INP9",
        dbf_type: DbFieldType::String,
        read_only: false,
    },
    FieldDesc {
        name: "A",
        dbf_type: DbFieldType::Double,
        read_only: false,
    },
    FieldDesc {
        name: "B",
        dbf_type: DbFieldType::Double,
        read_only: false,
    },
    FieldDesc {
        name: "C",
        dbf_type: DbFieldType::Double,
        read_only: false,
    },
    FieldDesc {
        name: "D",
        dbf_type: DbFieldType::Double,
        read_only: false,
    },
    FieldDesc {
        name: "E",
        dbf_type: DbFieldType::Double,
        read_only: false,
    },
    FieldDesc {
        name: "F",
        dbf_type: DbFieldType::Double,
        read_only: false,
    },
    FieldDesc {
        name: "G",
        dbf_type: DbFieldType::Double,
        read_only: false,
    },
    FieldDesc {
        name: "H",
        dbf_type: DbFieldType::Double,
        read_only: false,
    },
    FieldDesc {
        name: "I",
        dbf_type: DbFieldType::Double,
        read_only: false,
    },
    FieldDesc {
        name: "J",
        dbf_type: DbFieldType::Double,
        read_only: false,
    },
];

impl Record for PrintfRecord {
    fn record_type(&self) -> &'static str {
        "printf"
    }

    fn field_list(&self) -> &'static [FieldDesc] {
        PRINTF_FIELDS
    }

    fn uses_monitor_deadband(&self) -> bool {
        false
    }

    fn process(&mut self) -> CaResult<ProcessOutcome> {
        self.val = self.apply_fmt();
        Ok(ProcessOutcome::complete())
    }

    fn val(&self) -> Option<EpicsValue> {
        Some(EpicsValue::CharArray(self.val.as_bytes().to_vec()))
    }

    fn get_field(&self, name: &str) -> Option<EpicsValue> {
        match name {
            "VAL" => Some(EpicsValue::CharArray(self.val.as_bytes().to_vec())),
            "SIZV" => Some(EpicsValue::Short(self.sizv as i16)),
            "FMT" => Some(EpicsValue::String(self.fmt.clone())),
            _ => {
                if let Some(idx) = Self::inp_index(name) {
                    return Some(EpicsValue::String(self.inp_links[idx].clone()));
                }
                if let Some(idx) = Self::val_index(name) {
                    return Some(self.vals[idx].clone());
                }
                None
            }
        }
    }

    fn put_field(&mut self, name: &str, value: EpicsValue) -> CaResult<()> {
        match name {
            "SIZV" => {
                if let EpicsValue::Short(v) = value {
                    // C `init_record`: SIZV clamps to [16, 0x7fff].
                    let v = (v as i32).clamp(16, 0x7fff);
                    self.sizv = v as u16;
                }
            }
            "FMT" => {
                if let EpicsValue::String(s) = value {
                    self.fmt = s;
                } else {
                    return Err(CaError::TypeMismatch("FMT".into()));
                }
            }
            _ => {
                if let Some(idx) = Self::inp_index(name) {
                    if let EpicsValue::String(s) = value {
                        self.inp_links[idx] = s;
                    } else {
                        return Err(CaError::TypeMismatch(name.into()));
                    }
                } else if let Some(idx) = Self::val_index(name) {
                    // Store the raw value so `%s` can recover the
                    // string form of a string-typed input link.
                    self.vals[idx] = value;
                } else {
                    return Err(CaError::FieldNotFound(name.to_string()));
                }
            }
        }
        Ok(())
    }

    fn multi_input_links(&self) -> &[(&'static str, &'static str)] {
        &[
            ("INP0", "A"),
            ("INP1", "B"),
            ("INP2", "C"),
            ("INP3", "D"),
            ("INP4", "E"),
            ("INP5", "F"),
            ("INP6", "G"),
            ("INP7", "H"),
            ("INP8", "I"),
            ("INP9", "J"),
        ]
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    fn rec_with(fmt: &str) -> PrintfRecord {
        PrintfRecord {
            fmt: fmt.to_string(),
            ..Default::default()
        }
    }

    /// H-6: `%s` prints the input link's STRING content, not a number.
    #[test]
    fn percent_s_formats_string_input() {
        let mut rec = rec_with("name=%s");
        rec.vals[0] = EpicsValue::String("motor1".into());
        rec.process().unwrap();
        assert_eq!(rec.val, "name=motor1");
    }

    /// H-6: a string input survives even when other slots are numeric.
    #[test]
    fn percent_s_with_width_padding() {
        let mut rec = rec_with("[%8s]");
        rec.vals[0] = EpicsValue::String("ab".into());
        rec.process().unwrap();
        assert_eq!(rec.val, "[      ab]");
    }

    /// H-7: `%*d` reads the field width from the next input link.
    #[test]
    fn star_width_consumes_an_input() {
        let mut rec = rec_with("%*d");
        rec.vals[0] = EpicsValue::Long(6); // width
        rec.vals[1] = EpicsValue::Long(42); // value
        rec.process().unwrap();
        assert_eq!(rec.val, "    42");
    }

    /// H-7: `%ld` long modifier is consumed, not emitted literally.
    #[test]
    fn long_modifier_consumed() {
        let mut rec = rec_with("%ld");
        rec.vals[0] = EpicsValue::Long(99);
        rec.process().unwrap();
        assert_eq!(rec.val, "99");
    }

    /// H-7: `%ls` long-string conversion prints the string input.
    #[test]
    fn long_string_conversion() {
        let mut rec = rec_with("%ls");
        rec.vals[0] = EpicsValue::String("hello".into());
        rec.process().unwrap();
        assert_eq!(rec.val, "hello");
    }

    /// H-7: `%c` prints a single character.
    #[test]
    fn percent_c_formats_char() {
        let mut rec = rec_with("%c");
        rec.vals[0] = EpicsValue::Long(65); // 'A'
        rec.process().unwrap();
        assert_eq!(rec.val, "A");
    }

    /// L-2: `%#g` of zero keeps trailing zeros; plain `%g` is "0".
    #[test]
    fn g_zero_alt_form() {
        let mut rec = rec_with("%g");
        rec.vals[0] = EpicsValue::Double(0.0);
        rec.process().unwrap();
        assert_eq!(rec.val, "0");

        let mut rec = rec_with("%#.3g");
        rec.vals[0] = EpicsValue::Double(0.0);
        rec.process().unwrap();
        assert_eq!(rec.val, "0.00");
    }

    /// `%%` escapes a literal percent.
    #[test]
    fn percent_escape() {
        let mut rec = rec_with("100%%");
        rec.process().unwrap();
        assert_eq!(rec.val, "100%");
    }
}