use crate::*;
use crate::syntax::block::Item;
use crate::syntax::block::escape_string;
use crate::syntax::block::constructors::*;
use crate::gen::schema::*;

use convert_case::{Case, Casing};

use lazy_static::lazy_static;

use preserves::value::Map;
use preserves::value::NestedValue;
use preserves::value::Value;

use super::CompilerConfig;
use super::names;
use super::types;

#[derive(Clone, Copy)]
pub enum ModuleContextMode {
    TargetIOValue,
    TargetAny,
}

pub struct ModuleContext<'m> {
    pub module_path: ModulePath,
    pub config: &'m CompilerConfig,
    pub literals: Map<_Any, String>,
    pub typedefs: Vec<Item>,
    pub functiondefs: Vec<Item>,
    pub mode: ModuleContextMode,
}

pub struct FunctionContext<'a, 'm> {
    pub error_context: String,
    pub m: &'a mut ModuleContext<'m>,
    pub temp_counter: usize,
    pub captures: Vec<Capture>,
    pub capture_mode: CaptureMode,
}

pub struct Capture {
    pub field_name: String,
    pub ty: types::TField,
    pub source_expr: String,
}

pub enum CaptureMode {
    Definite,
    Indefinite(Vec<Item>),
}

lazy_static! {
    static ref ID_RE: regex::Regex = regex::Regex::new(r"^[a-zA-Z][a-zA-Z_0-9]*$").unwrap();
}

impl<'m> ModuleContext<'m> {
    pub fn new(config: &'m CompilerConfig, module_path: &ModulePath) -> Self {
        ModuleContext {
            module_path: module_path.to_owned(),
            config: config,
            literals: Map::new(),
            typedefs: Vec::new(),
            functiondefs: Vec::new(),
            mode: ModuleContextMode::TargetIOValue,
        }
    }

    pub fn define_literal(&mut self, v: &_Any) -> String {
        let prefix = format!("LIT_{}", self.literals.len());
        let next_id = match v.value() {
            Value::Boolean(b) => prefix + "_" + &b.to_string(),
            Value::Symbol(s) => if ID_RE.is_match(&s) { prefix + "_" + s } else { prefix },
            Value::String(s) => if ID_RE.is_match(&s) { prefix + "_" + s } else { prefix },
            Value::SignedInteger(n) => prefix + "_" + &n.to_string(),
            _ => prefix
        };
        let next_id = next_id.to_case(Case::UpperSnake);
        "&*".to_owned() + self.target_prefix() + "::" + self.literals.entry(v.clone()).or_insert(next_id)
    }

    pub fn define_type(&mut self, i: Item) {
        self.typedefs.push(i)
    }

    pub fn define_function<F: FnOnce(FunctionContext) -> Item>(&mut self, error_context: &str, f: F) {
        let i = f(FunctionContext::new(self, error_context));
        self.functiondefs.push(i)
    }

    pub fn render_ref(&self, r: &Ref) -> Item {
        match self.config.module_aliases.get(&r.module.0) {
            None =>
                if r.module.0.is_empty() {
                    item(r.name.to_owned())
                } else {
                    let mut items = Vec::new();
                    items.push(item(self.config.fully_qualified_module_prefix.to_owned()));
                    for p in &r.module.0 { items.push(item(names::render_modname(p))) }
                    items.push(item(r.name.to_owned()));
                    item(name(items))
                }
            Some(s) =>
                item(name![s.to_owned(), r.name.to_owned()])
        }
    }

    pub fn target(&self) -> &'static str {
        match self.mode {
            ModuleContextMode::TargetIOValue => "preserves::value::IOValue",
            ModuleContextMode::TargetAny => "_Any",
        }
    }

    pub fn target_prefix(&self) -> &'static str {
        match self.mode {
            ModuleContextMode::TargetIOValue => "_io_",
            ModuleContextMode::TargetAny => "_any_",
        }
    }
}

impl<'a, 'm> FunctionContext<'a, 'm> {
    pub fn new(m: &'a mut ModuleContext<'m>, error_context: &str) -> Self {
        FunctionContext {
            error_context: error_context.to_owned(),
            m: m,
            temp_counter: 0,
            captures: Vec::new(),
            capture_mode: CaptureMode::Definite,
        }
    }

    pub fn capture(&mut self, field_name: String, ty: types::TField, source_expr: String) {
        self.captures.push(Capture {
            field_name: field_name,
            ty: ty,
            source_expr: match self.capture_mode {
                CaptureMode::Definite =>
                    source_expr,
                CaptureMode::Indefinite(_) =>
                    format!("{}.ok_or_else(|| {:?})?", source_expr, self.conformance_err_code()),
            }
        })
    }

    pub fn lookup_capture(&self, field_name: &str) -> &Capture {
        for c in &self.captures {
            if c.field_name == field_name {
                return c;
            }
        }
        panic!("No capture for field {:?} available", field_name)
    }

    pub fn gentempname(&mut self) -> String {
        let i = self.temp_counter;
        self.temp_counter += 1;
        format!("_tmp{}", i)
    }

    pub fn declare_compound(&self, body: &mut Vec<Item>, name: &str, init_expr: Item) {
        body.push(item(seq!["let mut ", name.to_owned(), " = ", init_expr, ";"]));
    }

    pub fn define_atom(&mut self, body: &mut Vec<Item>, name: &str, val_expr: Item) {
        body.push(match &mut self.capture_mode {
            CaptureMode::Definite => item(seq!["let ", name.to_owned(), " = ", val_expr, ";"]),
            CaptureMode::Indefinite(items) => {
                items.push(item(seq!["let mut ", name.to_owned(), " = None;"]));
                item(seq![name.to_owned(), " = Some(", val_expr, ");"])
            }
        })
    }

    pub fn with_indefinite_mode<F: FnOnce(&mut Self) -> ()>(&mut self, f: F) -> Vec<Item> {
        let saved_mode = std::mem::replace(&mut self.capture_mode, CaptureMode::Indefinite(Vec::new()));
        f(self);
        match std::mem::replace(&mut self.capture_mode, saved_mode) {
            CaptureMode::Definite => panic!("corrupt capture_mode"),
            CaptureMode::Indefinite(declarations) => declarations,
        }
    }

    pub fn branch<R, F: FnOnce(&mut Self) -> R>(&mut self, f: F) -> R {
        let saved_temp_counter = self.temp_counter;
        let saved_capture_count = self.captures.len();
        let result = f(self);
        self.temp_counter = saved_temp_counter;
        self.captures.truncate(saved_capture_count);
        result
    }

    pub fn err_code(&self) -> Item {
        return item(seq!["Err", parens![self.conformance_err_code()]]);
    }

    pub fn conformance_err_code(&self) -> Item {
        return item(seq!["_support::ParseError::conformance_error", parens![
            escape_string(&(self.m.module_path.0.join(".") + "." + &self.error_context))]]);
    }
}