use rustc::mir;

use crate::traits::BuilderMethods;
use super::FunctionCx;
use super::LocalRef;
use super::OperandValue;
use crate::traits::*;

impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
    pub fn codegen_statement(
        &mut self,
        mut bx: Bx,
        statement: &mir::Statement<'tcx>
    ) -> Bx {
        debug!("codegen_statement(statement={:?})", statement);

        self.set_debug_loc(&mut bx, statement.source_info);
        match statement.kind {
            mir::StatementKind::Assign(ref place, ref rvalue) => {
                if let mir::Place::Base(mir::PlaceBase::Local(index)) = *place {
                    match self.locals[index] {
                        LocalRef::Place(cg_dest) => {
                            self.codegen_rvalue(bx, cg_dest, rvalue)
                        }
                        LocalRef::UnsizedPlace(cg_indirect_dest) => {
                            self.codegen_rvalue_unsized(bx, cg_indirect_dest, rvalue)
                        }
                        LocalRef::Operand(None) => {
                            let (bx, operand) = self.codegen_rvalue_operand(bx, rvalue);
                            self.locals[index] = LocalRef::Operand(Some(operand));
                            bx
                        }
                        LocalRef::Operand(Some(op)) => {
                            if !op.layout.is_zst() {
                                span_bug!(statement.source_info.span,
                                          "operand {:?} already assigned",
                                          rvalue);
                            }

                            // If the type is zero-sized, it's already been set here,
                            // but we still need to make sure we codegen the operand
                            self.codegen_rvalue_operand(bx, rvalue).0
                        }
                    }
                } else {
                    let cg_dest = self.codegen_place(&mut bx, place);
                    self.codegen_rvalue(bx, cg_dest, rvalue)
                }
            }
            mir::StatementKind::SetDiscriminant{ref place, variant_index} => {
                self.codegen_place(&mut bx, place)
                    .codegen_set_discr(&mut bx, variant_index);
                bx
            }
            mir::StatementKind::StorageLive(local) => {
                if let LocalRef::Place(cg_place) = self.locals[local] {
                    cg_place.storage_live(&mut bx);
                } else if let LocalRef::UnsizedPlace(cg_indirect_place) = self.locals[local] {
                    cg_indirect_place.storage_live(&mut bx);
                }
                bx
            }
            mir::StatementKind::StorageDead(local) => {
                if let LocalRef::Place(cg_place) = self.locals[local] {
                    cg_place.storage_dead(&mut bx);
                } else if let LocalRef::UnsizedPlace(cg_indirect_place) = self.locals[local] {
                    cg_indirect_place.storage_dead(&mut bx);
                }
                bx
            }
            mir::StatementKind::InlineAsm(ref asm) => {
                let outputs = asm.outputs.iter().map(|output| {
                    self.codegen_place(&mut bx, output)
                }).collect();

                let input_vals = asm.inputs.iter()
                    .fold(Vec::with_capacity(asm.inputs.len()), |mut acc, (span, input)| {
                        let op = self.codegen_operand(&mut bx, input);
                        if let OperandValue::Immediate(_) = op.val {
                            acc.push(op.immediate());
                        } else {
                            span_err!(bx.sess(), span.to_owned(), E0669,
                                     "invalid value for constraint in inline assembly");
                        }
                        acc
                });

                if input_vals.len() == asm.inputs.len() {
                    let res = bx.codegen_inline_asm(&asm.asm, outputs, input_vals);
                    if !res {
                        span_err!(bx.sess(), statement.source_info.span, E0668,
                                  "malformed inline assembly");
                    }
                }
                bx
            }
            mir::StatementKind::FakeRead(..) |
            mir::StatementKind::Retag { .. } |
            mir::StatementKind::AscribeUserType(..) |
            mir::StatementKind::Nop => bx,
        }
    }
}