//
// Copyright 2019, Google Inc.
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are
// met:
//
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//    * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
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// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Alternatively, this software may be distributed under the terms of the
// GNU General Public License ("GPL") version 2 as published by the Free
// Software Foundation.
//

use std::io::prelude::*;
use std::process::Command;

#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum LayoutNames {
    TopQuad,
    TopHalf,
    BottomHalf,
    BottomQuad,
}

#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub struct LayoutSizes {
    half_sz: i64,
    quad_sz: i64,
    rom_top: i64,
    bottom_half_top: i64,
    bottom_quad_top: i64,
    top_quad_bottom: i64,
}

pub fn get_layout_sizes(rom_sz: i64) -> Result<LayoutSizes, String> {
    if rom_sz <= 0 {
        return Err("invalid rom size provided".into());
    }
    if rom_sz & (rom_sz - 1) != 0 {
        return Err("invalid rom size, not a power of 2".into());
    }
    Ok(LayoutSizes {
        half_sz: rom_sz / 2,
        quad_sz: rom_sz / 4,
        rom_top: rom_sz - 1,
        bottom_half_top: (rom_sz / 2) - 1,
        bottom_quad_top: (rom_sz / 4) - 1,
        top_quad_bottom: (rom_sz / 4) * 3,
    })
}

pub fn layout_section(ls: &LayoutSizes, ln: LayoutNames) -> (&'static str, i64, i64) {
    match ln {
        LayoutNames::TopQuad => ("TOP_QUAD", ls.top_quad_bottom, ls.quad_sz),
        LayoutNames::TopHalf => ("TOP_HALF", ls.half_sz, ls.half_sz),
        LayoutNames::BottomHalf => ("BOTTOM_HALF", 0, ls.half_sz),
        LayoutNames::BottomQuad => ("BOTTOM_QUAD", 0, ls.quad_sz),
    }
}

pub fn construct_layout_file<F: Write>(mut target: F, ls: &LayoutSizes) -> std::io::Result<()> {
    writeln!(target, "000000:{:x} BOTTOM_QUAD", ls.bottom_quad_top)?;
    writeln!(target, "000000:{:x} BOTTOM_HALF", ls.bottom_half_top)?;
    writeln!(target, "{:x}:{:x} TOP_HALF", ls.half_sz, ls.rom_top)?;
    writeln!(target, "{:x}:{:x} TOP_QUAD", ls.top_quad_bottom, ls.rom_top)
}

pub fn toggle_hw_wp(dis: bool) -> Result<(), String> {
    // The easist way to toggle the harware write-protect is
    // to {dis}connect the battery (and/or open the WP screw).
    let s = if dis { "dis" } else { "" };
    info!("Prompt for hardware WP {}able", s);
    eprintln!(" > {}connect the battery (and/or open the WP screw)", s);
    pause();
    let wp = get_hardware_wp()?;
    if wp && dis {
        eprintln!("Hardware write protect is still ENABLED!");
        return toggle_hw_wp(dis);
    }
    if !wp && !dis {
        eprintln!("Hardware write protect is still DISABLED!");
        return toggle_hw_wp(dis);
    }
    Ok(())
}

pub fn ac_power_warning() {
    info!("*****************************");
    info!("AC power *must be* connected!");
    info!("*****************************");
    pause();
}

fn pause() {
    let mut stdout = std::io::stdout();
    // We want the cursor to stay at the end of the line, so we print without a newline
    // and flush manually.
    stdout.write(b"Press any key to continue...").unwrap();
    stdout.flush().unwrap();
    std::io::stdin().read(&mut [0]).unwrap();
}

pub fn get_hardware_wp() -> std::result::Result<bool, String> {
    let (_, wp) = parse_crosssystem(&collect_crosssystem()?)?;
    Ok(wp)
}

pub fn collect_crosssystem() -> Result<String, String> {
    let cmd = match Command::new("crossystem").output() {
        Ok(x) => x,
        Err(e) => return Err(format!("Failed to run crossystem: {}", e)),
    };

    if !cmd.status.success() {
        return Err(translate_command_error(&cmd).to_string());
    };

    Ok(String::from_utf8_lossy(&cmd.stdout).into_owned())
}

fn parse_crosssystem(s: &str) -> Result<(Vec<&str>, bool), &'static str> {
    // grep -v 'fwid +=' | grep -v 'hwid +='
    let sysinfo = s
        .split_terminator("\n")
        .filter(|s| !s.contains("fwid +=") && !s.contains("hwid +="));

    let state_line = match sysinfo.clone().filter(|s| s.starts_with("wpsw_cur")).next() {
        None => return Err("No wpsw_cur in system info"),
        Some(line) => line,
    };
    let wp_s_val = state_line
        .trim_start_matches("wpsw_cur")
        .trim_start_matches(' ')
        .trim_start_matches('=')
        .trim_start_matches(' ')
        .get(..1)
        .unwrap()
        .parse::<u32>();

    match wp_s_val {
        Ok(v) => {
            if v == 1 {
                return Ok((sysinfo.collect(), true));
            } else if v == 0 {
                return Ok((sysinfo.collect(), false));
            } else {
                return Err("Unknown state value");
            }
        }
        Err(_) => return Err("Cannot parse state value"),
    }
}

pub fn translate_command_error(output: &std::process::Output) -> std::io::Error {
    use std::io::{Error, ErrorKind};
    // There is two cases on failure;
    //  i. ) A bad exit code,
    //  ii.) A SIG killed us.
    match output.status.code() {
        Some(code) => {
            let e = format!(
                "{}\nExited with error code: {}",
                String::from_utf8_lossy(&output.stderr),
                code
            );
            Error::new(ErrorKind::Other, e)
        }
        None => Error::new(
            ErrorKind::Other,
            "Process terminated by a signal".to_string(),
        ),
    }
}

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

    #[test]
    fn construct_layout_file() {
        use super::{construct_layout_file, get_layout_sizes};

        let mut buf = Vec::new();
        construct_layout_file(
            &mut buf,
            &get_layout_sizes(0x10000).expect("64k is a valid chip size"),
        )
        .expect("no I/O errors expected");

        assert_eq!(
            &buf[..],
            &b"000000:3fff BOTTOM_QUAD\n\
               000000:7fff BOTTOM_HALF\n\
               8000:ffff TOP_HALF\n\
               c000:ffff TOP_QUAD\n"[..]
        );
    }

    #[test]
    fn get_layout_sizes() {
        use super::get_layout_sizes;

        assert_eq!(
            get_layout_sizes(-128).err(),
            Some("invalid rom size provided".into())
        );

        assert_eq!(
            get_layout_sizes(3 << 20).err(),
            Some("invalid rom size, not a power of 2".into())
        );

        assert_eq!(
            get_layout_sizes(64 << 10).unwrap(),
            LayoutSizes {
                half_sz: 0x8000,
                quad_sz: 0x4000,
                rom_top: 0xFFFF,
                bottom_half_top: 0x7FFF,
                bottom_quad_top: 0x3FFF,
                top_quad_bottom: 0xC000,
            }
        );
    }

    #[test]
    fn parse_crosssystem() {
        use super::parse_crosssystem;

        assert_eq!(
            parse_crosssystem("This is not the tool you are looking for").err(),
            Some("No wpsw_cur in system info")
        );

        assert_eq!(
            parse_crosssystem("wpsw_cur = ERROR").err(),
            Some("Cannot parse state value")
        );

        assert_eq!(
            parse_crosssystem("wpsw_cur = 3").err(),
            Some("Unknown state value")
        );

        assert_eq!(
            parse_crosssystem("wpsw_cur = 0"),
            Ok((vec!["wpsw_cur = 0"], false))
        );

        assert_eq!(
            parse_crosssystem("wpsw_cur = 1"),
            Ok((vec!["wpsw_cur = 1"], true))
        );

        assert_eq!(
            parse_crosssystem("wpsw_cur=1"),
            Ok((vec!["wpsw_cur=1"], true))
        );

        assert_eq!(
            parse_crosssystem(
                "fwid += 123wpsw_cur\n\
                 hwid += aaaaa\n\
                 wpsw_boot                  = 0                      # [RO/int]\n\
                 wpsw_cur                   = 1                      # [RO/int]\n"
            ),
            Ok((
                vec![
                    "wpsw_boot                  = 0                      # [RO/int]",
                    "wpsw_cur                   = 1                      # [RO/int]"
                ],
                true
            ))
        );
    }
}