"""
Generate sources with instruction info.
"""

import srcgen

def collect_instr_groups(targets):
    seen = set()
    groups = []
    for t in targets:
        for g in t.instruction_groups:
            if g not in seen:
                groups.append(g)
                seen.add(g)
    return groups

def gen_opcodes(groups, out_dir):
    """Generate opcode enumerations."""
    fmt = srcgen.Formatter()

    fmt.doc_comment('An instruction opcode.')
    fmt.doc_comment('')
    fmt.doc_comment('All instructions from all supported targets are present.')
    fmt.line('#[derive(Copy, Clone, PartialEq, Eq, Debug)]')
    instrs = []
    with fmt.indented('pub enum Opcode {', '}'):
        for g in groups:
            for i in g.instructions:
                instrs.append(i)
                # Build a doc comment.
                prefix = ', '.join(o.name for o in i.outs)
                if prefix:
                    prefix = prefix + ' = '
                suffix = ', '.join(o.name for o in i.ins)
                fmt.doc_comment('`{}{} {}`.'.format(prefix, i.name, suffix))
                # Enum variant itself.
                fmt.line(i.camel_name + ',')

    # Generate a private opcode_name function.
    with fmt.indented('fn opcode_name(opc: Opcode) -> &\'static str {', '}'):
        with fmt.indented('match opc {', '}'):
            for i in instrs:
                fmt.format('Opcode::{} => "{}",', i.camel_name, i.name)

    fmt.update_file('opcodes.rs', out_dir)

def generate(targets, out_dir):
    groups = collect_instr_groups(targets)
    gen_opcodes(groups, out_dir)