import driver.session;
import lib.llvm.llvm;
import middle.trans;
import std.Str;
import std.FS;

import lib.llvm.llvm.ModuleRef;
import lib.llvm.llvm.ValueRef;
import lib.llvm.mk_pass_manager;
import lib.llvm.mk_target_data;
import lib.llvm.mk_type_names;
import lib.llvm.False;
import lib.llvm.True;

tag output_type {
    output_type_none;
    output_type_bitcode;
    output_type_assembly;
    output_type_object;
}

fn llvm_err(session.session sess, str msg) {
    auto buf = llvm.LLVMRustGetLastError();
    if ((buf as uint) == 0u) {
        sess.err(msg);
    } else {
        sess.err(msg + ": " + Str.str_from_cstr(buf));
    }
    fail;
}

fn link_intrinsics(session.session sess, ModuleRef llmod) {
    auto path = FS.connect(sess.get_opts().sysroot, "intrinsics.bc");
    auto membuf =
        llvm.LLVMRustCreateMemoryBufferWithContentsOfFile(Str.buf(path));
    if ((membuf as uint) == 0u) {
        llvm_err(sess, "installation problem: couldn't open intrinstics.bc");
        fail;
    }

    auto llintrinsicsmod = llvm.LLVMRustParseBitcode(membuf);
    if ((llintrinsicsmod as uint) == 0u) {
        llvm_err(sess, "installation problem: couldn't parse intrinstics.bc");
        fail;
    }

    if (llvm.LLVMLinkModules(llmod, llintrinsicsmod) == False) {
        llvm_err(sess, "couldn't link the module with the intrinsics");
        fail;
    }
}

mod Write {
    fn is_object_or_assembly(output_type ot) -> bool {
        if (ot == output_type_assembly) {
            ret true;
        }
        if (ot == output_type_object) {
            ret true;
        }
        ret false;
    }

    // Decides what to call an intermediate file, given the name of the output
    // and the extension to use.
    fn mk_intermediate_name(str output_path, str extension) -> str {
        auto dot_pos = Str.index(output_path, '.' as u8);
        auto stem;
        if (dot_pos < 0) {
            stem = output_path;
        } else {
            stem = Str.substr(output_path, 0u, dot_pos as uint);
        }
        ret stem + "." + extension;
    }

    fn run_passes(session.session sess, ModuleRef llmod, str output) {
        link_intrinsics(sess, llmod);

        auto pm = mk_pass_manager();
        auto opts = sess.get_opts();

        auto td = mk_target_data(x86.get_data_layout());
        llvm.LLVMAddTargetData(td.lltd, pm.llpm);

        // TODO: run the linter here also, once there are llvm-c bindings for
        // it.

        // Generate a pre-optimization intermediate file if -save-temps was
        // specified.
        if (opts.save_temps) {
            alt (opts.output_type) {
                case (output_type_bitcode) {
                    if (opts.optimize) {
                        auto filename = mk_intermediate_name(output,
                                                             "no-opt.bc");
                        llvm.LLVMWriteBitcodeToFile(llmod,
                                                    Str.buf(filename));
                    }
                }
                case (_) {
                    auto filename = mk_intermediate_name(output, "bc");
                    llvm.LLVMWriteBitcodeToFile(llmod, Str.buf(filename));
                }
            }
        }

        // FIXME: This is mostly a copy of the bits of opt's -O2 that are
        // available in the C api.
        // FIXME2: We might want to add optimization levels like -O1, -O2,
        // -Os, etc
        // FIXME3: Should we expose and use the pass lists used by the opt
        // tool?
        if (opts.optimize) {
            auto fpm = mk_pass_manager();
            llvm.LLVMAddTargetData(td.lltd, fpm.llpm);
            llvm.LLVMAddStandardFunctionPasses(fpm.llpm, 2u);
            llvm.LLVMRunPassManager(fpm.llpm, llmod);

            // TODO: On -O3, use 275 instead of 225 for the inlining
            // threshold.
            llvm.LLVMAddStandardModulePasses(pm.llpm,
                                             2u,    // optimization level
                                             False, // optimize for size
                                             True,  // unit-at-a-time
                                             True,  // unroll loops
                                             True,  // simplify lib calls
                                             True,  // have exceptions
                                             225u); // inlining threshold
        }

        if (opts.verify) {
            llvm.LLVMAddVerifierPass(pm.llpm);
        }

        // TODO: Write .s if -c was specified and -save-temps was on.
        if (is_object_or_assembly(opts.output_type)) {
            let int LLVMAssemblyFile = 0;
            let int LLVMObjectFile = 1;
            let int LLVMNullFile = 2;
            auto FileType;
            if (opts.output_type == output_type_object) {
                FileType = LLVMObjectFile;
            } else {
                FileType = LLVMAssemblyFile;
            }

            // Write optimized bitcode if --save-temps was on.
            if (opts.save_temps) {
                alt (opts.output_type) {
                    case (output_type_bitcode) { /* nothing to do */ }
                    case (_) {
                        auto filename = mk_intermediate_name(output,
                                                             "opt.bc");
                        llvm.LLVMRunPassManager(pm.llpm, llmod);
                        llvm.LLVMWriteBitcodeToFile(llmod,
                                                    Str.buf(filename));
                        pm = mk_pass_manager();
                    }
                }
            }

            llvm.LLVMRustWriteOutputFile(pm.llpm, llmod,
                                         Str.buf(x86.get_target_triple()),
                                         Str.buf(output),
                                         FileType);
            llvm.LLVMDisposeModule(llmod);
            ret;
        }

        llvm.LLVMRunPassManager(pm.llpm, llmod);

        llvm.LLVMWriteBitcodeToFile(llmod, Str.buf(output));
        llvm.LLVMDisposeModule(llmod);
    }
}