use std::clone::Clone;
use std::fmt::{Debug, Formatter, Error};
use std::collections::{HashMap, HashSet};
use std::iter::FromIterator;


#[derive(Clone, PartialEq)]
pub struct ModelicaModel {
    pub name: String,
    pub description: Option<String>,
    pub components: Vec<Component>,
    pub equations: Vec<SimpleEquation>,
    pub connections: Vec<Connection>,
}

#[derive(Copy, Clone, PartialEq)]
pub enum ComponentPrefix {
    // incomplete: eg, can be parameter and input
    Flow,
    Stream,
    Input,
    Output,
    Discrete,
    Parameter,
    Constant,
}

#[derive(Clone, PartialEq)]
pub struct ComponentClause {
    pub prefix: Option<ComponentPrefix>,
    pub specifier: String,
    pub declarations: Vec<ComponentDeclaration>,
}

#[derive(Clone, PartialEq)]
pub struct ComponentDeclaration {
    pub name: String,
    pub dimensions: Option<Vec<i64>>,
    pub value: Option<Expr>,
    pub quantity: Option<String>,
    pub mods: HashMap<String, Expr>,
    pub description: Option<String>,
}

// This isn't part of the parse AST; it's a flattened helper type
#[derive(Clone, PartialEq)]
pub struct Component {
    pub prefix: Option<ComponentPrefix>,
    pub specifier: String,
    pub name: String,
    pub value: Option<Expr>,
    pub mods: HashMap<String, Expr>,
    pub description: Option<String>,
}

#[derive(Clone, PartialEq)]
pub struct Connection {
    pub a: String,
    pub b: String,
}

#[derive(Clone, PartialEq)]
pub struct SimpleEquation {
    pub lhs: Expr,
    pub rhs: Expr,
}

#[derive(Clone, PartialEq)]
pub enum Expr {
    Integer(i64),
    Float(f64),
    Boolean(bool),
    StringLiteral(String),
    Ident(String),
    Der(Box<Expr>),
    Sign(Box<Expr>),
    MathUnaryExpr(MathUnaryFunc, Box<Expr>),
    BinExpr(BinOperator, Box<Expr>, Box<Expr>),
    Array(Vec<Expr>),
}

#[derive(Copy, Clone, PartialEq)]
pub enum MathUnaryFunc {
    Abs,
    Sqrt,
    Sin,
    Cos,
    Tan,
    Asin,
    Acos,
    Atan,
    // TODO: atan2(x,y)
    Sinh,
    Cosh,
    Tanh,
    Exp,
    Log,
    Log10,
}

#[derive(Copy, Clone, PartialEq)]
pub enum BinOperator {
    Multiply,
    Divide,
    Add,
    Subtract,
}

//// Helpers

// This flattens the ComponentClause/ComponentDeclaration tree into a flat
// list of Components
pub fn collapse_components(clauses: &Vec<ComponentClause>) -> Vec<Component> {

    let mut vars: Vec<Component> = vec![];
    for clause in clauses {
        vars.extend(clause.declarations.iter().map(|ref dec|
            Component {
                prefix: clause.prefix.clone(),
                specifier: clause.specifier.clone(),
                name: dec.name.clone(),
                value: dec.value.clone(),
                mods: dec.mods.clone(),
                description: dec.description.clone(),
        }))
    }
    vars
}

impl ModelicaModel {

    pub fn get_constant_vars(&self) -> HashMap<String,Option<Expr>> {
        let mut binds = HashMap::new();
        // XXX: actually implement this...
        for c in &self.components {
            match c.prefix {
                Some(ComponentPrefix::Constant) => { binds.insert(c.name.clone(), Some(Expr::Integer(123))); },
                Some(ComponentPrefix::Parameter) => { binds.insert(c.name.clone(), Some(Expr::Float(4.56))); },
                _ => (),
            }
        }
        binds
    }

    // This crude function finds "unbound" variables: those which are not constants, parameters, or
    // the sole element on the LHS of an equation.
    // Bugs:
    //   if a var is on LHS and RHS of same equation
    pub fn get_free_vars(&self) -> HashSet<String> {
        // Start with components, and remove constants and parameters
        let vars = self.components.iter().filter(|v| match v.prefix {
                Some(ComponentPrefix::Constant) | Some(ComponentPrefix::Parameter) => false,
                _ => true,
            });


        // Remove LHS (bound) vars
        let mut outputs = vec![];
        for eq in self.equations.iter() {
            // TODO:
            if let Expr::Ident(ref symb) = eq.lhs {
                outputs.push(symb.to_string());
            }
        }
        let vars = vars.filter(|v| !outputs.contains(&v.name));

        HashSet::from_iter(vars.map(|c| c.name.clone()))
    }

}

impl Expr {

    // Order is undefined
    pub fn identifiers(&self) -> HashSet<String> {
        use self::Expr::*;
        match *self {
            Integer(_) | Float(_) | Boolean(_) | StringLiteral(_) => HashSet::new(),
            Ident(ref s) => {
                let mut hs = HashSet::new();
                hs.insert(s.to_string());
                hs
            },
            Der(ref e) | Sign(ref e) => e.identifiers(),
            MathUnaryExpr(_, ref e) => e.identifiers(),
            BinExpr(_, ref e1, ref e2) => {
                let mut hs = e1.identifiers();
                hs.extend(e2.identifiers());
                hs
            },
            Array(ref el) => {
                let mut all: HashSet<String> = HashSet::new();
                for e in el {
                    all.extend(e.identifiers());
                }
                all
            }
        }
    }

    pub fn contains(&self, ident: &str) -> bool{
        self.identifiers().contains(ident)
    }
}

impl SimpleEquation {

    // Order is undefined
    pub fn identifiers(&self) -> HashSet<String> {
        let mut hs = self.lhs.identifiers();
        hs.extend(self.rhs.identifiers());
        hs
    }

    pub fn contains(&self, ident: &str) -> bool{
        let s = &ident.to_string();
        self.lhs.identifiers().contains(s) || self.rhs.identifiers().contains(s)
    }
}

//// Debug Implementations

impl Debug for ModelicaModel {
    fn fmt(&self, fmt: &mut Formatter) -> Result<(), Error> {
        try!(write!(fmt, "model {}\n", self.name));
        if let Some(ref desc) = self.description {
            try!(write!(fmt, "  \"{}\"\n", desc));
        }
        for v in self.components.iter() {
            try!(write!(fmt, "  {:?};\n", v));
        }
        try!(write!(fmt, "equation\n"));
        for c in self.connections.iter() {
            try!(write!(fmt, "  {:?};\n", c));
        }
        for e in self.equations.iter() {
            try!(write!(fmt, "  {:?};\n", e));
        }
        write!(fmt, "end {};\n", self.name)
    }
}

impl Debug for ComponentPrefix {
    fn fmt(&self, fmt: &mut Formatter) -> Result<(), Error> {
        use self::ComponentPrefix::*;
        write!(fmt, "{}", 
            match *self {
                Flow => "flow",
                Stream => "stream",
                Input => "input",
                Output => "output",
                Discrete => "discrete",
                Parameter => "parameter",
                Constant => "constant",
            })
    }
}

impl Debug for Component {
    fn fmt(&self, fmt: &mut Formatter) -> Result<(), Error> {
        write!(fmt, "{}{} {}",
            match self.prefix {
                Some(p) => format!("{:?} ", p),
                None => "".to_string(),
            },
            self.specifier,
            self.name,
        )
    }
}

impl Debug for Connection {
    fn fmt(&self, fmt: &mut Formatter) -> Result<(), Error> {
        write!(fmt, "connect({}, {})", self.a, self.b)
    }
}

impl Debug for SimpleEquation {
    fn fmt(&self, fmt: &mut Formatter) -> Result<(), Error> {
        write!(fmt, "{:?} = {:?}", self.lhs, self.rhs)
    }
}

impl Debug for Expr {
    fn fmt(&self, fmt: &mut Formatter) -> Result<(), Error> {
        use self::Expr::*;
        match *self {
            Integer(e) => write!(fmt, "{}", e),
            Float(e) => write!(fmt, "{}", e),
            Boolean(e) => write!(fmt, "{}", e),
            StringLiteral(ref e) => write!(fmt, "\"{}\"", e),
            Ident(ref e) => write!(fmt, "{}", e),
            Der(ref e) => write!(fmt, "der({:?})", e),
            Sign(ref e) => write!(fmt, "sign({:?})", e),
            MathUnaryExpr(func, ref e) => write!(fmt, "{:?}({:?})", func, e),
            BinExpr(op, ref l, ref r) => write!(fmt, "({:?} {:?} {:?})", l, op, r),
            Array(ref el) => {
                try!(write!(fmt, "["));
                for e in el {
                    // XXX: not last comma
                    try!(write!(fmt, "{:?},", e));
                }
                write!(fmt, "]")
            },
        }
    }
}

impl Debug for BinOperator {
    fn fmt(&self, fmt: &mut Formatter) -> Result<(), Error> {
        use self::BinOperator::*;
        match *self {
            Multiply => write!(fmt, "*"),
            Divide => write!(fmt, "/"),
            Add => write!(fmt, "+"),
            Subtract => write!(fmt, "-"),
        }
    }
}

impl Debug for MathUnaryFunc {
    fn fmt(&self, fmt: &mut Formatter) -> Result<(), Error> {
        use self::MathUnaryFunc::*;
        match *self {
            Abs =>  write!(fmt, "abs"),
            Sqrt => write!(fmt, "sqrt"),
            Sin =>  write!(fmt, "sin"),
            Cos =>  write!(fmt, "cos"),
            Tan =>  write!(fmt, "tan"),
            Asin => write!(fmt, "asin"),
            Acos => write!(fmt, "acos"),
            Atan => write!(fmt, "atan"),
            Sinh => write!(fmt, "sinh"),
            Cosh => write!(fmt, "cosh"),
            Tanh => write!(fmt, "tanh"),
            Exp =>  write!(fmt, "exp"),
            Log =>  write!(fmt, "log"),
            Log10 => write!(fmt, "log10"),
        }
    }
}