use crate::exporter_error::PeerEntryParseError;
use std::collections::HashMap;
use std::convert::TryFrom;

#[derive(Debug, Default, Clone)]
pub(crate) struct PeerEntry<'a> {
    pub public_key: &'a str,
    pub allowed_ips: &'a str,
    pub name: Option<&'a str>,
}

#[inline]
fn after_char(s: &str, c_split: char) -> &str {
    let mut p: usize = 0;
    for c in s.chars().into_iter() {
        if c == c_split {
            return &s[p + 1..];
        } else {
            p += c.len_utf8();
        }
    }
    s
}

fn parse_peer_entry<'a>(lines: &[&'a str]) -> Result<PeerEntry<'a>, PeerEntryParseError> {
    let mut public_key = "";
    let mut allowed_ips = "";
    let mut name = None;

    for line in lines {
        if line.starts_with("PublicKey") {
            public_key = after_char(line, '=').trim();
        } else if line.starts_with("AllowedIPs") {
            allowed_ips = after_char(line, '=').trim();
        } else if line.starts_with("#") {
            name = Some(line[1..].trim());
        }
    }

    // Sanity checks
    if public_key == "" {
        let lines_owned: Vec<String> = lines.into_iter().map(|line| line.to_string()).collect();
        Err(PeerEntryParseError::PublicKeyNotFound { lines: lines_owned })
    } else if allowed_ips == "" {
        let lines_owned: Vec<String> = lines.into_iter().map(|line| line.to_string()).collect();
        Err(PeerEntryParseError::AllowedIPsEntryNotFound { lines: lines_owned })
    } else {
        Ok(PeerEntry {
            public_key,
            allowed_ips,
            name, // name can be None
        })
    }
}

pub(crate) fn parse<'a>(
    txt: &'a str,
) -> Result<HashMap<&'a str, PeerEntry<'a>>, PeerEntryParseError> {
    let mut ht = HashMap::new();

    let mut v_blocks = Vec::new();
    let mut cur_block: Option<Vec<&str>> = None;

    for line in txt.lines().into_iter() {
        if line.starts_with("[") {
            if let Some(inner_cur_block) = cur_block {
                // close the block
                v_blocks.push(inner_cur_block);
                cur_block = None;
            }

            if line == "[Peer]" {
                // start a new block
                cur_block = Some(Vec::new());
            }
        } else {
            // push the line if we are in a block (only if not empty)
            if let Some(inner_cur_block) = &mut cur_block {
                if line != "" {
                    inner_cur_block.push(line);
                }
            }
        }
    }

    if let Some(cur_block) = cur_block {
        // we have a leftover block
        v_blocks.push(cur_block);
    }

    println!("v_blocks == {:?}", v_blocks);

    for block in &v_blocks {
        let p = parse_peer_entry(block)?;
        ht.insert(p.public_key, p);
    }

    println!("ht == {:?}", ht);

    Ok(ht)
}

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

    const TEXT: &'static str = "
ListenPort = 51820
PrivateKey = my_super_secret_private_key
# PreUp = iptables -t nat -A POSTROUTING -s 10.70.0.0/24  -o enp7s0 -j MASQUERADE
# PostDown = iptables -t nat -D POSTROUTING -s 10.70.0.0/24  -o enp7s0 -j MASQUERADE

[Peer]
# OnePlus 6T
PublicKey = 2S7mA0vEMethCNQrJpJKE81/JmhgtB+tHHLYQhgM6kk=
AllowedIPs = 10.70.0.2/32

[Peer]
# varch.local (laptop)
PublicKey = qnoxQoQI8KKMupLnSSureORV0wMmH7JryZNsmGVISzU=
AllowedIPs = 10.70.0.3/32

[Peer]
# cantarch
PublicKey = L2UoJZN7RmEKsMmqaJgKG0m1S2Zs2wd2ptAf+kb3008=
AllowedIPs = 10.70.0.4/32

[Peer]
# frcognoarch
PublicKey = MdVOIPKt9K2MPj/sO2NlWQbOnFJ6L/qX80mmhQwsUlA=
AllowedIPs = 10.70.0.50/32

[Peer]
# frcognowin10
PublicKey = lqYcojJMsIZXMUw1heAFbQHBoKjCEaeo7M1WXDh/KWc=
AllowedIPs = 10.70.0.40/32

[Peer]
# OnePlus 5T
PublicKey = 928vO9Lf4+Mo84cWu4k1oRyzf0AR7FTGoPKHGoTMSHk=
AllowedIPs = 10.70.0.80/32
";

    #[test]
    fn test_parse() {
        let a = parse(TEXT);
        println!("{:?}", a);
    }

    #[test]
    fn test_parse_and_serialize() {}
}