local unique_name = require"bon".unique_name

local function pass_destandardify(chu)
    local function is_builtin_method(c)
        if c.type ~= 'dot' then
            return false
        end
        
        if c.a.et and c.a.et.type == 'list' and c.b == 'pop' then
            return {change_stmt = function(stmt)
                assert(stmt.type == 'call')
                
                local temp = {et = stmt.what.a.et, name = unique_name()}
                
                return {
                    {
                        type = 'let',
                        var = temp,
                        expr = stmt.what.a
                    },
                    {
                        type = 'assign',
                        dest = {
                            type = 'index',
                            what = {type = 'var', which = temp, et = temp.et},
                            idx = {type = 'lengthof', sub = {type = 'var', which = temp, et = temp.et}, et = {type = 'integer'}}
                        },
                        src = {type = 'null', et = {type = 'null'}}
                    },
                }
            end}
        end
        
        return false
    end
    
    if chu.type == "chunk" then
        for k, t in pairs(chu.types) do
            for _, m in pairs(t.members) do
                if m.type == "field" then
                    -- Do nothing.
                elseif m.type == "static" then
                    pass_destandardify(m.value)
                else
                    error("Invalid AST")
                end
            end
        end
        
        local stmtIdx = 1
        while stmtIdx <= #chu.stmts do
            local stmt = chu.stmts[stmtIdx]
            
            local builtinmethod = stmt.type == 'call' and is_builtin_method(stmt.what)
            if builtinmethod then
                table.remove(chu.stmts, stmtIdx)
                for p, o in ipairs(builtinmethod.change_stmt(stmt)) do
                    table.insert(chu.stmts, stmtIdx + p - 1, o)
                end
            else
                pass_destandardify(stmt)
                stmtIdx = stmtIdx + 1
            end
        end
    elseif chu.type == 'function' then
        pass_destandardify(chu.chunk)
    elseif chu.type == 'if' then
        for i = 1, #chu do
            pass_destandardify(chu[i].chu)
        end
        if chu.elsa then
            pass_destandardify(chu.elsa)
        end
    elseif chu.type == 'fori' then
        pass_destandardify(chu.chu)
    elseif chu.type == 'loop' then
        pass_destandardify(chu.chu)
    end
end

return pass_destandardify