// This file is part of the uutils coreutils package.
//
// (c) Tyler Steele <tyler.steele@protonmail.com>
//
// For the full copyright and license information, please view the LICENSE
// file that was distributed with this source code.
// spell-checker:ignore ctty, ctable, iseek, oseek, iconvflags, oconvflags parseargs outfile oconv

#[cfg(test)]
mod unit_tests;

use super::{ConversionMode, IConvFlags, IFlags, Num, OConvFlags, OFlags, Settings, StatusLevel};
use crate::conversion_tables::ConversionTable;
use std::error::Error;
use uucore::display::Quotable;
use uucore::error::UError;
use uucore::parse_size::{ParseSizeError, Parser as SizeParser};
use uucore::show_warning;

/// Parser Errors describe errors with parser input
#[derive(Debug, PartialEq, Eq)]
pub enum ParseError {
    UnrecognizedOperand(String),
    MultipleFmtTable,
    MultipleUCaseLCase,
    MultipleBlockUnblock,
    MultipleExclNoCreate,
    FlagNoMatch(String),
    ConvFlagNoMatch(String),
    MultiplierStringParseFailure(String),
    MultiplierStringOverflow(String),
    BlockUnblockWithoutCBS,
    StatusLevelNotRecognized(String),
    Unimplemented(String),
    BsOutOfRange(String),
    InvalidNumber(String),
}

/// Contains a temporary state during parsing of the arguments
#[derive(Debug, PartialEq)]
pub struct Parser {
    infile: Option<String>,
    outfile: Option<String>,
    ibs: usize,
    obs: usize,
    cbs: Option<usize>,
    skip: Num,
    seek: Num,
    count: Option<Num>,
    conv: ConvFlags,
    iflag: IFlags,
    oflag: OFlags,
    status: Option<StatusLevel>,
}

impl Default for Parser {
    fn default() -> Self {
        Self {
            ibs: 512,
            obs: 512,
            cbs: None,
            infile: None,
            outfile: None,
            skip: Num::Blocks(0),
            seek: Num::Blocks(0),
            count: None,
            conv: ConvFlags::default(),
            iflag: IFlags::default(),
            oflag: OFlags::default(),
            status: None,
        }
    }
}

#[derive(Debug, Default, PartialEq, Eq)]
pub struct ConvFlags {
    ascii: bool,
    ebcdic: bool,
    ibm: bool,
    ucase: bool,
    lcase: bool,
    block: bool,
    unblock: bool,
    swab: bool,
    sync: bool,
    noerror: bool,
    sparse: bool,
    excl: bool,
    nocreat: bool,
    notrunc: bool,
    fdatasync: bool,
    fsync: bool,
}

#[derive(Clone, Copy, PartialEq)]
enum Conversion {
    Ascii,
    Ebcdic,
    Ibm,
}

#[derive(Clone, Copy)]
enum Case {
    Lower,
    Upper,
}

#[derive(Clone, Copy)]
enum Block {
    Block(usize),
    Unblock(usize),
}

/// Return an Unimplemented error when the target is not Linux or Android
macro_rules! linux_only {
    ($s: expr, $val: expr) => {
        if cfg!(any(target_os = "linux", target_os = "android")) {
            $val
        } else {
            return Err(ParseError::Unimplemented($s.to_string()).into());
        }
    };
}

impl Parser {
    pub(crate) fn new() -> Self {
        Self::default()
    }

    pub(crate) fn parse(self, operands: &[&str]) -> Result<Settings, ParseError> {
        self.read(operands)?.validate()
    }

    pub(crate) fn read(mut self, operands: &[&str]) -> Result<Self, ParseError> {
        for operand in operands {
            self.parse_operand(operand)?;
        }

        Ok(self)
    }

    pub(crate) fn validate(self) -> Result<Settings, ParseError> {
        let conv = self.conv;
        let conversion = match (conv.ascii, conv.ebcdic, conv.ibm) {
            (false, false, false) => None,
            (true, false, false) => Some(Conversion::Ascii),
            (false, true, false) => Some(Conversion::Ebcdic),
            (false, false, true) => Some(Conversion::Ibm),
            _ => return Err(ParseError::MultipleFmtTable),
        };

        let case = match (conv.ucase, conv.lcase) {
            (false, false) => None,
            (true, false) => Some(Case::Upper),
            (false, true) => Some(Case::Lower),
            (true, true) => return Err(ParseError::MultipleUCaseLCase),
        };

        let non_ascii = matches!(conversion, Some(Conversion::Ascii));
        let conversion_table = get_ctable(conversion, case);

        if conv.nocreat && conv.excl {
            return Err(ParseError::MultipleExclNoCreate);
        }

        // The GNU docs state that
        // - ascii implies unblock
        // - ebcdic and ibm imply block
        // This has a side effect in how it's implemented in GNU, because this errors:
        //     conv=block,unblock
        // but these don't:
        //     conv=ascii,block,unblock
        //     conv=block,ascii,unblock
        //     conv=block,unblock,ascii
        //     conv=block conv=unblock conv=ascii
        let block = if let Some(cbs) = self.cbs {
            match conversion {
                Some(Conversion::Ascii) => Some(Block::Unblock(cbs)),
                Some(_) => Some(Block::Block(cbs)),
                None => match (conv.block, conv.unblock) {
                    (false, false) => None,
                    (true, false) => Some(Block::Block(cbs)),
                    (false, true) => Some(Block::Unblock(cbs)),
                    (true, true) => return Err(ParseError::MultipleBlockUnblock),
                },
            }
        } else if conv.block || conv.unblock {
            return Err(ParseError::BlockUnblockWithoutCBS);
        } else {
            None
        };

        let iconv = IConvFlags {
            mode: conversion_mode(conversion_table, block, non_ascii, conv.sync),
            swab: conv.swab,
            sync: if conv.sync {
                if block.is_some() {
                    Some(b' ')
                } else {
                    Some(0u8)
                }
            } else {
                None
            },
            noerror: conv.noerror,
        };

        let oconv = OConvFlags {
            sparse: conv.sparse,
            excl: conv.excl,
            nocreat: conv.nocreat,
            notrunc: conv.notrunc,
            fdatasync: conv.fdatasync,
            fsync: conv.fsync,
        };

        let skip = self
            .skip
            .force_bytes_if(self.iflag.skip_bytes)
            .to_bytes(self.ibs as u64);

        let seek = self
            .seek
            .force_bytes_if(self.oflag.seek_bytes)
            .to_bytes(self.obs as u64);

        let count = self.count.map(|c| c.force_bytes_if(self.iflag.count_bytes));

        Ok(Settings {
            skip,
            seek,
            count,
            iconv,
            oconv,
            ibs: self.ibs,
            obs: self.obs,
            infile: self.infile,
            outfile: self.outfile,
            iflags: self.iflag,
            oflags: self.oflag,
            status: self.status,
        })
    }

    fn parse_operand(&mut self, operand: &str) -> Result<(), ParseError> {
        match operand.split_once('=') {
            None => return Err(ParseError::UnrecognizedOperand(operand.to_string())),
            Some((k, v)) => match k {
                "bs" => {
                    let bs = self.parse_bytes(k, v)?;
                    self.ibs = bs;
                    self.obs = bs;
                }
                "cbs" => self.cbs = Some(self.parse_bytes(k, v)?),
                "conv" => self.parse_conv_flags(v)?,
                "count" => self.count = Some(self.parse_n(v)?),
                "ibs" => self.ibs = self.parse_bytes(k, v)?,
                "if" => self.infile = Some(v.to_string()),
                "iflag" => self.parse_input_flags(v)?,
                "obs" => self.obs = self.parse_bytes(k, v)?,
                "of" => self.outfile = Some(v.to_string()),
                "oflag" => self.parse_output_flags(v)?,
                "seek" | "oseek" => self.seek = self.parse_n(v)?,
                "skip" | "iseek" => self.skip = self.parse_n(v)?,
                "status" => self.status = Some(self.parse_status_level(v)?),
                _ => return Err(ParseError::UnrecognizedOperand(operand.to_string())),
            },
        }
        Ok(())
    }

    fn parse_n(&self, val: &str) -> Result<Num, ParseError> {
        let n = parse_bytes_with_opt_multiplier(val)?;
        Ok(if val.ends_with('B') {
            Num::Bytes(n)
        } else {
            Num::Blocks(n)
        })
    }

    fn parse_bytes(&self, arg: &str, val: &str) -> Result<usize, ParseError> {
        parse_bytes_with_opt_multiplier(val)?
            .try_into()
            .map_err(|_| ParseError::BsOutOfRange(arg.to_string()))
    }

    fn parse_status_level(&self, val: &str) -> Result<StatusLevel, ParseError> {
        match val {
            "none" => Ok(StatusLevel::None),
            "noxfer" => Ok(StatusLevel::Noxfer),
            "progress" => Ok(StatusLevel::Progress),
            _ => Err(ParseError::StatusLevelNotRecognized(val.to_string())),
        }
    }

    #[allow(clippy::cognitive_complexity)]
    fn parse_input_flags(&mut self, val: &str) -> Result<(), ParseError> {
        let i = &mut self.iflag;
        for f in val.split(',') {
            match f {
                // Common flags
                "cio" => return Err(ParseError::Unimplemented(f.to_string())),
                "direct" => linux_only!(f, i.direct = true),
                "directory" => linux_only!(f, i.directory = true),
                "dsync" => linux_only!(f, i.dsync = true),
                "sync" => linux_only!(f, i.sync = true),
                "nocache" => linux_only!(f, i.nocache = true),
                "nonblock" => linux_only!(f, i.nonblock = true),
                "noatime" => linux_only!(f, i.noatime = true),
                "noctty" => linux_only!(f, i.noctty = true),
                "nofollow" => linux_only!(f, i.nofollow = true),
                "nolinks" => return Err(ParseError::Unimplemented(f.to_string())),
                "binary" => return Err(ParseError::Unimplemented(f.to_string())),
                "text" => return Err(ParseError::Unimplemented(f.to_string())),

                // Input-only flags
                "fullblock" => i.fullblock = true,
                "count_bytes" => i.count_bytes = true,
                "skip_bytes" => i.skip_bytes = true,
                // GNU silently ignores oflags given as iflag.
                "append" | "seek_bytes" => {}
                _ => return Err(ParseError::FlagNoMatch(f.to_string())),
            }
        }
        Ok(())
    }

    #[allow(clippy::cognitive_complexity)]
    fn parse_output_flags(&mut self, val: &str) -> Result<(), ParseError> {
        let o = &mut self.oflag;
        for f in val.split(',') {
            match f {
                // Common flags
                "cio" => return Err(ParseError::Unimplemented(val.to_string())),
                "direct" => linux_only!(f, o.direct = true),
                "directory" => linux_only!(f, o.directory = true),
                "dsync" => linux_only!(f, o.dsync = true),
                "sync" => linux_only!(f, o.sync = true),
                "nocache" => linux_only!(f, o.nocache = true),
                "nonblock" => linux_only!(f, o.nonblock = true),
                "noatime" => linux_only!(f, o.noatime = true),
                "noctty" => linux_only!(f, o.noctty = true),
                "nofollow" => linux_only!(f, o.nofollow = true),
                "nolinks" => return Err(ParseError::Unimplemented(f.to_string())),
                "binary" => return Err(ParseError::Unimplemented(f.to_string())),
                "text" => return Err(ParseError::Unimplemented(f.to_string())),

                // Output-only flags
                "append" => o.append = true,
                "seek_bytes" => o.seek_bytes = true,
                // GNU silently ignores iflags given as oflag.
                "fullblock" | "count_bytes" | "skip_bytes" => {}
                _ => return Err(ParseError::FlagNoMatch(f.to_string())),
            }
        }
        Ok(())
    }

    fn parse_conv_flags(&mut self, val: &str) -> Result<(), ParseError> {
        let c = &mut self.conv;
        for f in val.split(',') {
            match f {
                // Conversion
                "ascii" => c.ascii = true,
                "ebcdic" => c.ebcdic = true,
                "ibm" => c.ibm = true,

                // Case
                "lcase" => c.lcase = true,
                "ucase" => c.ucase = true,

                // Block
                "block" => c.block = true,
                "unblock" => c.unblock = true,

                // Other input
                "swab" => c.swab = true,
                "sync" => c.sync = true,
                "noerror" => c.noerror = true,

                // Output
                "sparse" => c.sparse = true,
                "excl" => c.excl = true,
                "nocreat" => c.nocreat = true,
                "notrunc" => c.notrunc = true,
                "fdatasync" => c.fdatasync = true,
                "fsync" => c.fsync = true,
                _ => return Err(ParseError::ConvFlagNoMatch(f.to_string())),
            }
        }
        Ok(())
    }
}

impl std::fmt::Display for ParseError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::UnrecognizedOperand(arg) => {
                write!(f, "Unrecognized operand '{arg}'")
            }
            Self::MultipleFmtTable => {
                write!(
                    f,
                    "Only one of conv=ascii conv=ebcdic or conv=ibm may be specified"
                )
            }
            Self::MultipleUCaseLCase => {
                write!(f, "Only one of conv=lcase or conv=ucase may be specified")
            }
            Self::MultipleBlockUnblock => {
                write!(f, "Only one of conv=block or conv=unblock may be specified")
            }
            Self::MultipleExclNoCreate => {
                write!(f, "Only one ov conv=excl or conv=nocreat may be specified")
            }
            Self::FlagNoMatch(arg) => {
                // Additional message about 'dd --help' is displayed only in this situation.
                write!(
                    f,
                    "invalid input flag: ‘{}’\nTry '{} --help' for more information.",
                    arg,
                    uucore::execution_phrase()
                )
            }
            Self::ConvFlagNoMatch(arg) => {
                write!(f, "Unrecognized conv=CONV -> {arg}")
            }
            Self::MultiplierStringParseFailure(arg) => {
                write!(f, "Unrecognized byte multiplier -> {arg}")
            }
            Self::MultiplierStringOverflow(arg) => {
                write!(
                    f,
                    "Multiplier string would overflow on current system -> {arg}"
                )
            }
            Self::BlockUnblockWithoutCBS => {
                write!(f, "conv=block or conv=unblock specified without cbs=N")
            }
            Self::StatusLevelNotRecognized(arg) => {
                write!(f, "status=LEVEL not recognized -> {arg}")
            }
            Self::BsOutOfRange(arg) => {
                write!(f, "{arg}=N cannot fit into memory")
            }
            Self::Unimplemented(arg) => {
                write!(f, "feature not implemented on this system -> {arg}")
            }
            Self::InvalidNumber(arg) => {
                write!(f, "invalid number: ‘{arg}’")
            }
        }
    }
}

impl Error for ParseError {}

impl UError for ParseError {
    fn code(&self) -> i32 {
        1
    }
}

fn show_zero_multiplier_warning() {
    show_warning!(
        "{} is a zero multiplier; use {} if that is intended",
        "0x".quote(),
        "00x".quote()
    );
}

/// Parse bytes using str::parse, then map error if needed.
fn parse_bytes_only(s: &str) -> Result<u64, ParseError> {
    s.parse()
        .map_err(|_| ParseError::MultiplierStringParseFailure(s.to_string()))
}

/// Parse a number of bytes from the given string, assuming no `'x'` characters.
///
/// The `'x'` character means "multiply the number before the `'x'` by
/// the number after the `'x'`". In order to compute the numbers
/// before and after the `'x'`, use this function, which assumes there
/// are no `'x'` characters in the string.
///
/// A suffix `'c'` means multiply by 1, `'w'` by 2, and `'b'` by
/// 512. You can also use standard block size suffixes like `'k'` for
/// 1024.
///
/// # Errors
///
/// If a number cannot be parsed or if the multiplication would cause
/// an overflow.
///
/// # Examples
///
/// ```rust,ignore
/// assert_eq!(parse_bytes_no_x("123", "123").unwrap(), 123);
/// assert_eq!(parse_bytes_no_x("2c", "2c").unwrap(), 2 * 1);
/// assert_eq!(parse_bytes_no_x("3w", "3w").unwrap(), 3 * 2);
/// assert_eq!(parse_bytes_no_x("2b", "2b").unwrap(), 2 * 512);
/// assert_eq!(parse_bytes_no_x("2k", "2k").unwrap(), 2 * 1024);
/// ```
fn parse_bytes_no_x(full: &str, s: &str) -> Result<u64, ParseError> {
    let parser = SizeParser {
        capital_b_bytes: true,
        ..Default::default()
    };
    let (num, multiplier) = match (s.find('c'), s.rfind('w'), s.rfind('b')) {
        (None, None, None) => match parser.parse(s) {
            Ok(n) => (n, 1),
            Err(ParseSizeError::InvalidSuffix(_) | ParseSizeError::ParseFailure(_)) => {
                return Err(ParseError::InvalidNumber(full.to_string()))
            }
            Err(ParseSizeError::SizeTooBig(_)) => {
                return Err(ParseError::MultiplierStringOverflow(full.to_string()))
            }
        },
        (Some(i), None, None) => (parse_bytes_only(&s[..i])?, 1),
        (None, Some(i), None) => (parse_bytes_only(&s[..i])?, 2),
        (None, None, Some(i)) => (parse_bytes_only(&s[..i])?, 512),
        _ => return Err(ParseError::MultiplierStringParseFailure(full.to_string())),
    };
    num.checked_mul(multiplier)
        .ok_or_else(|| ParseError::MultiplierStringOverflow(full.to_string()))
}

/// Parse byte and multiplier like 512, 5KiB, or 1G.
/// Uses uucore::parse_size, and adds the 'w' and 'c' suffixes which are mentioned
/// in dd's info page.
pub fn parse_bytes_with_opt_multiplier(s: &str) -> Result<u64, ParseError> {
    // TODO On my Linux system, there seems to be a maximum block size of 4096 bytes:
    //
    //     $ printf "%0.sa" {1..10000} | dd bs=4095 count=1 status=none | wc -c
    //     4095
    //     $ printf "%0.sa" {1..10000} | dd bs=4k count=1 status=none | wc -c
    //     4096
    //     $ printf "%0.sa" {1..10000} | dd bs=4097 count=1 status=none | wc -c
    //     4096
    //     $ printf "%0.sa" {1..10000} | dd bs=5k count=1 status=none | wc -c
    //     4096
    //

    // Split on the 'x' characters. Each component will be parsed
    // individually, then multiplied together.
    let parts: Vec<&str> = s.split('x').collect();
    if parts.len() == 1 {
        parse_bytes_no_x(s, parts[0])
    } else {
        let mut total: u64 = 1;
        for part in parts {
            if part == "0" {
                show_zero_multiplier_warning();
            }
            let num = parse_bytes_no_x(s, part)?;
            total = total
                .checked_mul(num)
                .ok_or_else(|| ParseError::InvalidNumber(s.to_string()))?;
        }
        Ok(total)
    }
}

fn get_ctable(
    conversion: Option<Conversion>,
    case: Option<Case>,
) -> Option<&'static ConversionTable> {
    use crate::conversion_tables::*;
    Some(match (conversion, case) {
        (None, None) => return None,
        (Some(conv), None) => match conv {
            Conversion::Ascii => &EBCDIC_TO_ASCII,
            Conversion::Ebcdic => &ASCII_TO_EBCDIC,
            Conversion::Ibm => &ASCII_TO_IBM,
        },
        (None, Some(case)) => match case {
            Case::Lower => &ASCII_UCASE_TO_LCASE,
            Case::Upper => &ASCII_LCASE_TO_UCASE,
        },
        (Some(conv), Some(case)) => match (conv, case) {
            (Conversion::Ascii, Case::Upper) => &EBCDIC_TO_ASCII_LCASE_TO_UCASE,
            (Conversion::Ascii, Case::Lower) => &EBCDIC_TO_ASCII_UCASE_TO_LCASE,
            (Conversion::Ebcdic, Case::Upper) => &ASCII_TO_EBCDIC_LCASE_TO_UCASE,
            (Conversion::Ebcdic, Case::Lower) => &ASCII_TO_EBCDIC_UCASE_TO_LCASE,
            (Conversion::Ibm, Case::Upper) => &ASCII_TO_IBM_UCASE_TO_LCASE,
            (Conversion::Ibm, Case::Lower) => &ASCII_TO_IBM_LCASE_TO_UCASE,
        },
    })
}

/// Given the various command-line parameters, determine the conversion mode.
///
/// The `conv` command-line option can take many different values,
/// each of which may combine with others. For example, `conv=ascii`,
/// `conv=lcase`, `conv=sync`, and so on. The arguments to this
/// function represent the settings of those various command-line
/// parameters. This function translates those settings to a
/// [`ConversionMode`].
fn conversion_mode(
    ctable: Option<&'static ConversionTable>,
    block: Option<Block>,
    is_ascii: bool,
    is_sync: bool,
) -> Option<ConversionMode> {
    match (ctable, block) {
        (Some(ct), None) => Some(ConversionMode::ConvertOnly(ct)),
        (Some(ct), Some(Block::Block(cbs))) => {
            if is_ascii {
                Some(ConversionMode::ConvertThenBlock(ct, cbs, is_sync))
            } else {
                Some(ConversionMode::BlockThenConvert(ct, cbs, is_sync))
            }
        }
        (Some(ct), Some(Block::Unblock(cbs))) => {
            if is_ascii {
                Some(ConversionMode::ConvertThenUnblock(ct, cbs))
            } else {
                Some(ConversionMode::UnblockThenConvert(ct, cbs))
            }
        }
        (None, Some(Block::Block(cbs))) => Some(ConversionMode::BlockOnly(cbs, is_sync)),
        (None, Some(Block::Unblock(cbs))) => Some(ConversionMode::UnblockOnly(cbs)),
        (None, None) => None,
    }
}

#[cfg(test)]
mod tests {

    use crate::parseargs::parse_bytes_with_opt_multiplier;

    #[test]
    fn test_parse_bytes_with_opt_multiplier() {
        assert_eq!(parse_bytes_with_opt_multiplier("123").unwrap(), 123);
        assert_eq!(parse_bytes_with_opt_multiplier("123c").unwrap(), 123); // 123 * 1
        assert_eq!(parse_bytes_with_opt_multiplier("123w").unwrap(), 123 * 2);
        assert_eq!(parse_bytes_with_opt_multiplier("123b").unwrap(), 123 * 512);
        assert_eq!(parse_bytes_with_opt_multiplier("123x3").unwrap(), 123 * 3);
        assert_eq!(parse_bytes_with_opt_multiplier("123k").unwrap(), 123 * 1024);
        assert_eq!(parse_bytes_with_opt_multiplier("1x2x3").unwrap(), 6); // 1 * 2 * 3

        assert_eq!(
            parse_bytes_with_opt_multiplier("1wx2cx3w").unwrap(),
            2 * 2 * (3 * 2) // (1 * 2) * (2 * 1) * (3 * 2)
        );
        assert!(parse_bytes_with_opt_multiplier("123asdf").is_err());
    }
}