// Package builder is the compiler driver of TinyGo. It takes in a package name
// and an output path, and outputs an executable. It manages the entire
// compilation pipeline in between.
package builder

import (
	"errors"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"strconv"
	"strings"

	"github.com/tinygo-org/tinygo/compileopts"
	"github.com/tinygo-org/tinygo/compiler"
	"github.com/tinygo-org/tinygo/goenv"
	"github.com/tinygo-org/tinygo/interp"
	"github.com/tinygo-org/tinygo/transform"
	"tinygo.org/x/go-llvm"
)

// Build performs a single package to executable Go build. It takes in a package
// name, an output path, and set of compile options and from that it manages the
// whole compilation process.
//
// The error value may be of type *MultiError. Callers will likely want to check
// for this case and print such errors individually.
func Build(pkgName, outpath string, config *compileopts.Config, action func(string) error) error {
	// Compile Go code to IR.
	machine, err := compiler.NewTargetMachine(config)
	if err != nil {
		return err
	}
	mod, extraFiles, errs := compiler.Compile(pkgName, machine, config)
	if errs != nil {
		return newMultiError(errs)
	}

	if config.Options.PrintIR {
		fmt.Println("; Generated LLVM IR:")
		fmt.Println(mod.String())
	}
	if err := llvm.VerifyModule(mod, llvm.PrintMessageAction); err != nil {
		return errors.New("verification error after IR construction")
	}

	err = interp.Run(mod, config.DumpSSA())
	if err != nil {
		return err
	}
	if err := llvm.VerifyModule(mod, llvm.PrintMessageAction); err != nil {
		return errors.New("verification error after interpreting runtime.initAll")
	}

	if config.GOOS() != "darwin" {
		transform.ApplyFunctionSections(mod) // -ffunction-sections
	}

	// Browsers cannot handle external functions that have type i64 because it
	// cannot be represented exactly in JavaScript (JS only has doubles). To
	// keep functions interoperable, pass int64 types as pointers to
	// stack-allocated values.
	// Use -wasm-abi=generic to disable this behaviour.
	if config.Options.WasmAbi == "js" && strings.HasPrefix(config.Triple(), "wasm") {
		err := transform.ExternalInt64AsPtr(mod)
		if err != nil {
			return err
		}
	}

	// Optimization levels here are roughly the same as Clang, but probably not
	// exactly.
	errs = nil
	switch config.Options.Opt {
	case "none", "0":
		errs = transform.Optimize(mod, config, 0, 0, 0) // -O0
	case "1":
		errs = transform.Optimize(mod, config, 1, 0, 0) // -O1
	case "2":
		errs = transform.Optimize(mod, config, 2, 0, 225) // -O2
	case "s":
		errs = transform.Optimize(mod, config, 2, 1, 225) // -Os
	case "z":
		errs = transform.Optimize(mod, config, 2, 2, 5) // -Oz, default
	default:
		errs = []error{errors.New("unknown optimization level: -opt=" + config.Options.Opt)}
	}
	if len(errs) > 0 {
		return newMultiError(errs)
	}
	if err := llvm.VerifyModule(mod, llvm.PrintMessageAction); err != nil {
		return errors.New("verification failure after LLVM optimization passes")
	}

	// On the AVR, pointers can point either to flash or to RAM, but we don't
	// know. As a temporary fix, load all global variables in RAM.
	// In the future, there should be a compiler pass that determines which
	// pointers are flash and which are in RAM so that pointers can have a
	// correct address space parameter (address space 1 is for flash).
	if strings.HasPrefix(config.Triple(), "avr") {
		transform.NonConstGlobals(mod)
		if err := llvm.VerifyModule(mod, llvm.PrintMessageAction); err != nil {
			return errors.New("verification error after making all globals non-constant on AVR")
		}
	}

	// Generate output.
	outext := filepath.Ext(outpath)
	switch outext {
	case ".o":
		llvmBuf, err := machine.EmitToMemoryBuffer(mod, llvm.ObjectFile)
		if err != nil {
			return err
		}
		return ioutil.WriteFile(outpath, llvmBuf.Bytes(), 0666)
	case ".bc":
		data := llvm.WriteBitcodeToMemoryBuffer(mod).Bytes()
		return ioutil.WriteFile(outpath, data, 0666)
	case ".ll":
		data := []byte(mod.String())
		return ioutil.WriteFile(outpath, data, 0666)
	default:
		// Act as a compiler driver.

		// Create a temporary directory for intermediary files.
		dir, err := ioutil.TempDir("", "tinygo")
		if err != nil {
			return err
		}
		defer os.RemoveAll(dir)

		// Write the object file.
		objfile := filepath.Join(dir, "main.o")
		llvmBuf, err := machine.EmitToMemoryBuffer(mod, llvm.ObjectFile)
		if err != nil {
			return err
		}
		err = ioutil.WriteFile(objfile, llvmBuf.Bytes(), 0666)
		if err != nil {
			return err
		}

		// Prepare link command.
		executable := filepath.Join(dir, "main")
		tmppath := executable // final file
		ldflags := append(config.LDFlags(), "-o", executable, objfile)

		// Load builtins library from the cache, possibly compiling it on the
		// fly.
		if config.Target.RTLib == "compiler-rt" {
			librt, err := CompilerRT.Load(config.Triple())
			if err != nil {
				return err
			}
			ldflags = append(ldflags, librt)
		}

		// Add libc.
		if config.Target.Libc == "picolibc" {
			libc, err := Picolibc.Load(config.Triple())
			if err != nil {
				return err
			}
			ldflags = append(ldflags, libc)
		}

		// Compile extra files.
		root := goenv.Get("TINYGOROOT")
		for i, path := range config.ExtraFiles() {
			abspath := filepath.Join(root, path)
			outpath := filepath.Join(dir, "extra-"+strconv.Itoa(i)+"-"+filepath.Base(path)+".o")
			err := runCCompiler(config.Target.Compiler, append(config.CFlags(), "-c", "-o", outpath, abspath)...)
			if err != nil {
				return &commandError{"failed to build", path, err}
			}
			ldflags = append(ldflags, outpath)
		}

		// Compile C files in packages.
		for i, file := range extraFiles {
			outpath := filepath.Join(dir, "pkg"+strconv.Itoa(i)+"-"+filepath.Base(file)+".o")
			err := runCCompiler(config.Target.Compiler, append(config.CFlags(), "-c", "-o", outpath, file)...)
			if err != nil {
				return &commandError{"failed to build", file, err}
			}
			ldflags = append(ldflags, outpath)
		}

		// Link the object files together.
		err = link(config.Target.Linker, ldflags...)
		if err != nil {
			return &commandError{"failed to link", executable, err}
		}

		if config.Options.PrintSizes == "short" || config.Options.PrintSizes == "full" {
			sizes, err := loadProgramSize(executable)
			if err != nil {
				return err
			}
			if config.Options.PrintSizes == "short" {
				fmt.Printf("   code    data     bss |   flash     ram\n")
				fmt.Printf("%7d %7d %7d | %7d %7d\n", sizes.Code, sizes.Data, sizes.BSS, sizes.Code+sizes.Data, sizes.Data+sizes.BSS)
			} else {
				fmt.Printf("   code  rodata    data     bss |   flash     ram | package\n")
				for _, name := range sizes.sortedPackageNames() {
					pkgSize := sizes.Packages[name]
					fmt.Printf("%7d %7d %7d %7d | %7d %7d | %s\n", pkgSize.Code, pkgSize.ROData, pkgSize.Data, pkgSize.BSS, pkgSize.Flash(), pkgSize.RAM(), name)
				}
				fmt.Printf("%7d %7d %7d %7d | %7d %7d | (sum)\n", sizes.Sum.Code, sizes.Sum.ROData, sizes.Sum.Data, sizes.Sum.BSS, sizes.Sum.Flash(), sizes.Sum.RAM())
				fmt.Printf("%7d       - %7d %7d | %7d %7d | (all)\n", sizes.Code, sizes.Data, sizes.BSS, sizes.Code+sizes.Data, sizes.Data+sizes.BSS)
			}
		}

		// Get an Intel .hex file or .bin file from the .elf file.
		if outext == ".hex" || outext == ".bin" || outext == ".gba" {
			tmppath = filepath.Join(dir, "main"+outext)
			err := objcopy(executable, tmppath)
			if err != nil {
				return err
			}
		} else if outext == ".uf2" {
			// Get UF2 from the .elf file.
			tmppath = filepath.Join(dir, "main"+outext)
			err := convertELFFileToUF2File(executable, tmppath, config.Target.UF2FamilyID)
			if err != nil {
				return err
			}
		}
		return action(tmppath)
	}
}