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use std::fs;
use std::path;
use std::collections::HashMap;
use std::vec::Vec;

pub struct Db {
    path: String,
    tables: Vec<Table>
}

#[derive(Debug)]
pub enum Column {
    Str,
    LongStr,
    I32,
    Byte,
}

#[derive(Debug)]
pub struct TableSpec {
    pub data: HashMap<String, Column>
}

#[derive(Debug)]
pub struct Table {
    spec: TableSpec,
    name: String,
    path: String,
}

#[macro_export]
macro_rules! table {
    ( $( $n:ident : $t:ident ),* ) => {{
        extern crate kiln;
        use std::collections::HashMap;
        let mut v: HashMap<String, kiln::Column> = HashMap::new();
        $(
            let s = stringify!($n).to_string();
            match stringify!($t) {
                "str" => v.insert(s, kiln::Column::Str),
                "block" => v.insert(s, kiln::Column::LongStr),
                "i32" => v.insert(s, kiln::Column::I32),
                "byte" => v.insert(s, kiln::Column::Byte),
                // So far just skips invalid tokens.
                _ => None
            };
        )*
        kiln::TableSpec{data:v}
    }}
}

impl Db {
    pub fn new(path: &str) -> Result<Self, std::io::Error> {
        if path::Path::new(path).exists() {
            Ok(Self {
                path: path.to_string(),
                tables: Vec::new(),
            })
        } else {
            fs::create_dir(path)?;
            Ok(Self {
                path: path.to_string(),
                tables: Vec::new(),
            })
        }
    }

    fn spec(&self, table: &str) -> TableSpec {
        let t = path::Path::new(&self.path).join(table);
        let spec = t.join("_spec");

        let mut v: HashMap<String, Column> = HashMap::new();

        for i in fs::read_dir(spec).unwrap() {
            let col = i.unwrap().path();
            let data = match &*fs::read_to_string(&col)
                .expect("Unable to read specfile") {
                    "i32" => Some(Column::I32),
                    "byte" => Some(Column::Byte),
                    "str" => Some(Column::Str),
                    "longstr" => Some(Column::LongStr),
                    _ => None
                };
            v.insert(col.file_name()
                        .expect("Error in parsing specfile, could not get name of file")
                        .to_string_lossy()
                        .to_string()
                    , data.unwrap());
        }
        TableSpec{data:v}
    }

    pub fn create(&self, name: &str, tablespec: TableSpec) -> Result<Table, std::io::Error> {
        let p = path::Path::new(&self.path).join(name);
        println!("{:?}", p.clone().as_path().exists());
        if !&p.as_path().exists() {
            println!("Creating");
            fs::create_dir(p.clone())?;
            let spec = p.join("_spec");
            let idx = p.join("_index");
            fs::create_dir(&spec)?;
            fs::create_dir(&idx)?;
            fs::create_dir(p.join("_data"))?;

            // Create a specfile and index for each col
            for (name, t) in tablespec.data.into_iter() {
                // Write type to specfile
                fs::write(&spec.join(&name), 
                    match t {
                        Column::I32 => "i32",
                        Column::Byte => "byte",
                        Column::Str => "str",
                        Column::LongStr => "longstr",
                    })?;
                fs::create_dir(&idx.join(&name))?;
            }
            Ok(
                Table {
                    spec: self.spec(name),
                    name: name.to_string(),
                    path: p.to_str().unwrap().to_string(),
                }
            )
        } else {
            Err(std::io::Error::new(
                std::io::ErrorKind::PermissionDenied,
                "DB already exists!"
            ))
        }
    }
}