use crate::addressing::{Address, Addressable};
use crate::database::inner::models;
use crate::util::hash::{decode, hash, Hash, Hashable};
use anyhow::{anyhow, Result};
use serde::{Deserialize, Serialize};
use std::convert::TryFrom;
use std::io::{Cursor, Write};

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct InEntry {
    pub entity: Option<Address>,
    pub attribute: String,
    pub value: EntryValue,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Entry {
    pub entity: Address,
    pub attribute: String,
    pub value: EntryValue,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct InvariantEntry {
    pub attribute: String,
    pub value: EntryValue,
}

#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[serde(tag = "t", content = "c")]
pub enum EntryValue {
    Value(serde_json::Value),
    Address(Address),
    Invalid,
}

impl TryFrom<&models::Entry> for Entry {
    type Error = anyhow::Error;

    fn try_from(e: &models::Entry) -> Result<Self, Self::Error> {
        Ok(Entry {
            entity: Address::decode(&e.entity)?,
            attribute: e.attribute.clone(),
            value: e.value.parse().unwrap(),
        })
    }
}

impl TryFrom<&Entry> for models::Entry {
    type Error = anyhow::Error;

    fn try_from(e: &Entry) -> Result<Self, Self::Error> {
        Ok(models::Entry {
            identity: e.address()?.encode()?,
            entity: e.entity.encode()?,
            attribute: e.attribute.clone(),
            value: e.value.to_string()?,
        })
    }
}

impl TryFrom<&InvariantEntry> for Entry {
    type Error = anyhow::Error;

    fn try_from(invariant: &InvariantEntry) -> Result<Self, Self::Error> {
        Ok(Entry {
            entity: invariant.entity()?,
            attribute: invariant.attribute.clone(),
            value: invariant.value.clone(),
        })
    }
}

impl TryFrom<InEntry> for Entry {
    type Error = anyhow::Error;

    fn try_from(in_entry: InEntry) -> Result<Self, Self::Error> {
        match in_entry.entity {
            Some(entity) => Ok(Entry {
                entity,
                attribute: in_entry.attribute,
                value: in_entry.value,
            }),
            None => Ok(Entry::try_from(&InvariantEntry {
                attribute: in_entry.attribute,
                value: in_entry.value,
            })?),
        }
    }
}

impl InvariantEntry {
    pub fn entity(&self) -> Result<Address> {
        let mut entity = Cursor::new(vec![0u8; 0]);
        entity.write_all(self.attribute.as_bytes())?;
        entity.write_all(self.value.to_string()?.as_bytes())?;
        Ok(Address::Hash(hash(entity.into_inner())))
    }
}

impl std::fmt::Display for Entry {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{} | {} | {}", self.entity, self.attribute, self.value)
    }
}

impl Hashable for Entry {
    fn hash(self: &Entry) -> Result<Hash> {
        let mut result = Cursor::new(vec![0u8; 0]);
        result.write_all(self.entity.encode()?.as_slice())?;
        result.write_all(self.attribute.as_bytes())?;
        result.write_all(self.value.to_string()?.as_bytes())?;
        Ok(hash(result.get_ref()))
    }
}

impl Hashable for InvariantEntry {
    fn hash(&self) -> Result<Hash> {
        Entry::try_from(self)?.hash()
    }
}

impl Addressable for Entry {}
impl Addressable for InvariantEntry {}

impl EntryValue {
    pub fn to_string(&self) -> Result<String> {
        let (type_char, content) = match self {
            EntryValue::Value(value) => ('J', serde_json::to_string(value)?),
            EntryValue::Address(address) => ('O', address.to_string()),
            EntryValue::Invalid => return Err(anyhow!("Cannot serialize invalid Entity value.")),
        };

        Ok(format!("{}{}", type_char, content))
    }
}

impl std::fmt::Display for EntryValue {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let (entry_type, entry_value) = match self {
            EntryValue::Address(address) => ("ADDRESS", address.to_string()),
            EntryValue::Value(value) => (
                "VALUE",
                serde_json::to_string(value).unwrap_or_else(|_| String::from("?!?!?!")),
            ),
            EntryValue::Invalid => ("INVALID", "INVALID".to_string()),
        };
        write!(f, "{}: {}", entry_type, entry_value)
    }
}

impl std::str::FromStr for EntryValue {
    type Err = std::convert::Infallible;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        if s.len() < 2 {
            Ok(EntryValue::Invalid)
        } else {
            let (type_char, content) = s.split_at(1);
            match (type_char, content) {
                ("J", content) => {
                    if let Ok(value) = serde_json::from_str(content) {
                        Ok(EntryValue::Value(value))
                    } else {
                        Ok(EntryValue::Invalid)
                    }
                }
                ("O", content) => {
                    if let Ok(addr) = decode(content).and_then(|v| Address::decode(&v)) {
                        Ok(EntryValue::Address(addr))
                    } else {
                        Ok(EntryValue::Invalid)
                    }
                }
                _ => Ok(EntryValue::Invalid),
            }
        }
    }
}