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use crate::code_page::CodePage;
use crate::serde_helpers::StringSerde;
use std::fmt::{self, Debug, Formatter};
use std::iter::{self};
use serde::{Serialize, Deserialize, Serializer, Deserializer};
use serde::ser::SerializeSeq;
use serde::ser::Error as ser_Error;
use serde::de::{self, DeserializeSeed};
use serde_serialize_seed::{SerializeSeed, ValueWithSeed};

#[derive(Clone, Debug, PartialOrd, PartialEq, Ord, Eq, Hash)]
pub struct StringZ {
    pub string: String,
    pub has_tail_zero: bool
}

impl Default for StringZ {
    fn default() -> StringZ { StringZ { string: String::default(), has_tail_zero: true } }
}

impl<T: Into<String>> From<T> for StringZ {
    fn from(t: T) -> StringZ { StringZ { string: t.into(), has_tail_zero: true } }
}

#[derive(Clone)]
pub struct StringZSerde {
    pub code_page: Option<CodePage>,
}

impl SerializeSeed for StringZSerde {
    type Value = StringZ;

    fn serialize<S>(&self, value: &Self::Value, serializer: S) -> Result<S::Ok, S::Error> where S: Serializer {
        if serializer.is_human_readable() {
            let mut carets = value.string.len() - value.string.rfind(|x| x != '^')
                .map_or(0, |i| i + value.string[i..].chars().next().unwrap().len_utf8());
            if !value.has_tail_zero {
                carets += 1;
            }
            let mut s = String::with_capacity(value.string.len() + carets);
            s.push_str(&value.string);
            s.extend(iter::repeat('^').take(carets));
            s.serialize(serializer)
        } else {
            if !value.has_tail_zero && value.string.as_bytes().last() == Some(&0) {
                return Err(S::Error::custom("zero-terminated string value has tail zero"));
            }
            let mut s = String::with_capacity(value.string.len() + if value.has_tail_zero { 1 } else { 0 });
            s.push_str(&value.string);
            if value.has_tail_zero {
                s.push('\0');
            }
            ValueWithSeed(s.as_str(), StringSerde { code_page: self.code_page, len: None }).serialize(serializer)
        }
    }
}

impl<'de> DeserializeSeed<'de> for StringZSerde {
    type Value = StringZ;

    fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, D::Error> where D: Deserializer<'de> {
        if deserializer.is_human_readable() {
            let mut string = String::deserialize(deserializer)?;
            let carets = string.len() - string.rfind(|x| x != '^').map_or(0, |i| i + string[i..].chars().next().unwrap().len_utf8());
            let has_tail_zero = carets % 2 == 0;
            let carets = (carets + 1) / 2;
            string.truncate(string.len() - carets);
            Ok(StringZ { string, has_tail_zero })
        } else {
            let mut string = StringSerde { code_page: self.code_page, len: None }.deserialize(deserializer)?;
            let has_tail_zero = string.as_bytes().last() == Some(&0);
            if has_tail_zero {
                string.truncate(string.len() - 1);
            }
            Ok(StringZ { string, has_tail_zero })
        }
    }
}

#[derive(Clone, Debug, PartialOrd, PartialEq, Ord, Eq, Hash)]
pub struct StringZList {
    pub vec: Vec<String>,
    pub has_tail_zero: bool
}

impl Default for StringZList {
    fn default() -> StringZList { StringZList { vec: Vec::default(), has_tail_zero: true } }
}

impl<T: Into<Vec<String>>> From<T> for StringZList {
    fn from(t: T) -> StringZList { StringZList { vec: t.into(), has_tail_zero: true } }
}

#[derive(Clone)]
pub struct StringZListSerde {
    pub code_page: Option<CodePage>
}

impl SerializeSeed for StringZListSerde {
    type Value = StringZList;

    fn serialize<S>(&self, value: &Self::Value, serializer: S) -> Result<S::Ok, S::Error> where S: Serializer {
        if serializer.is_human_readable() {
            let mut carets = value.vec.len() - value.vec.iter().rposition(|x| x != "^").map_or(0, |i| i + 1);
            if !value.has_tail_zero {
                carets += 1;
            }
            let mut serializer = serializer.serialize_seq(Some(value.vec.len() + carets))?;
            for s in &value.vec {
                serializer.serialize_element(s)?;
            }
            for _ in 0..carets {
                serializer.serialize_element("^")?;
            }
            serializer.end()
        } else {
            let mut capacity = 0;
            for s in &value.vec {
                if s.contains('\0') {
                    return Err(S::Error::custom("zero-terminated string list item contains zero byte"));
                }
                capacity += s.len() + 1;
            }
            let mut text = String::with_capacity(capacity);
            for s in &value.vec {
                text.push_str(s);
                text.push('\0');
            }
            if !value.has_tail_zero {
                text.truncate(text.len() - 1);
            }
            ValueWithSeed(text.as_str(), StringSerde { code_page: self.code_page, len: None }).serialize(serializer)
        }
    }
}

struct StringZListHRDeVisitor;

impl<'de> de::Visitor<'de> for StringZListHRDeVisitor {
    type Value = StringZList;

    fn expecting(&self, f: &mut Formatter) -> fmt::Result {
        write!(f, "string sequence")
    }

    fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error> where A: de::SeqAccess<'de> {
        let mut vec: Vec<String> = seq.size_hint().map_or_else(Vec::new, Vec::with_capacity);
        while let Some(line) = seq.next_element()? {
            vec.push(line);
        }
        let carets = vec.len() - vec.iter().rposition(|x| x != "^").map_or(0, |i| i + 1);
        let has_tail_zero = carets % 2 == 0;
        let carets = (carets + 1) / 2;
        vec.truncate(vec.len() - carets);
        Ok(StringZList { vec, has_tail_zero })
    }
}

impl<'de> DeserializeSeed<'de> for StringZListSerde {
    type Value = StringZList;

    fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, D::Error> where D: Deserializer<'de> {
        if deserializer.is_human_readable() {
            deserializer.deserialize_seq(StringZListHRDeVisitor)
        } else {
            let v = StringSerde { code_page: self.code_page, len: None }.deserialize(deserializer)?;
            let has_tail_zero = v.as_bytes().last() == Some(&0);
            let v = if has_tail_zero { &v[.. v.len() - 1] } else { &v };
            Ok(StringZList { vec: v.split('\0').map(|x| x.into()).collect(), has_tail_zero })
        }
    }
}

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

    #[test]
    fn string_into_string_z() {
        let z = Field::StringZ(String::from("Y").into());
        if let Field::StringZ(z) = z {
            assert_eq!(z.string, "Y");
        } else {
            panic!()
        }
        let z = Field::StringZ("Y".into());
        if let Field::StringZ(z) = z {
            assert_eq!(z.string, "Y");
        } else {
            panic!()
        }
    }
}