package go4k

import (
	"bufio"
	"fmt"
	"regexp"
	"strconv"
	"strings"
)

func ParseAsm(asmcode string) (*Song, error) {
	paramReg, err := regexp.Compile(`(?:([a-zA-Z]\w*)\s*\(\s*([0-9]+)\s*\)|([0-9]+))`) // matches FOO(42), groups "FOO" and "42" OR just numbers
	if err != nil {
		return nil, fmt.Errorf("error compiling paramReg: %v", err)
	}
	parseParams := func(s string) (map[string]int, []int, error) {
		matches := paramReg.FindAllStringSubmatch(s, 256)
		namedParams := map[string]int{}
		unnamedParams := make([]int, 0)
		for _, match := range matches {
			if match[1] == "" { // the second part of OR fired
				val, err := strconv.Atoi(match[3])
				if err != nil {
					return nil, nil, fmt.Errorf("error converting %v to integer, which is unexpected as regexp matches only numbers: %v", match[3], err)
				}
				unnamedParams = append(unnamedParams, val)
			} else {
				val, err := strconv.Atoi(match[2])
				if err != nil {
					return nil, nil, fmt.Errorf("error converting %v to integer, which is unexpected as regexp matches only numbers: %v", match[2], err)
				}
				namedParams[strings.ToLower(match[1])] = val
			}
		}
		return namedParams, unnamedParams, nil
	}
	wordReg, err := regexp.Compile(`\s*([a-zA-Z_][a-zA-Z0-9_]*)([^;\n]*)`) // matches a word and "the rest", until newline or a comment
	if err != nil {
		return nil, err
	}
	toBytes := func(ints []int) []byte {
		ret := []byte{}
		for _, v := range ints {
			ret = append(ret, byte(v))
		}
		return ret
	}
	var song Song
	scanner := bufio.NewScanner(strings.NewReader(asmcode))
	for scanner.Scan() {
		line := scanner.Text()
		macroMatch := wordReg.FindStringSubmatch(line)
		if macroMatch == nil {
			continue
		}
		word, rest := macroMatch[1], macroMatch[2]
		namedParams, unnamedParams, err := parseParams(rest)
		if err != nil {
			return nil, fmt.Errorf("error parsing parameters: %v", err)
		}
		switch word {
		case "BEGIN_SONG":
			song = Song{BPM: namedParams["bpm"], Patterns: nil, Tracks: nil, Patch: Patch{}, Output16Bit: namedParams["output_16bit"] == 1, Hold: byte(namedParams["hold"])}
		case "PATTERN":
			song.Patterns = append(song.Patterns, toBytes(unnamedParams))
		case "TRACK":
			song.Tracks = append(song.Tracks, Track{namedParams["voices"], toBytes(unnamedParams)})
		case "BEGIN_INSTRUMENT":
			song.Patch.Instruments = append(song.Patch.Instruments, Instrument{NumVoices: namedParams["voices"], Units: []Unit{}})
		case "DELTIME":
			song.Patch.DelayTimes = append(song.Patch.DelayTimes, unnamedParams...)
		case "SAMPLE_OFFSET":
			song.Patch.SampleOffsets = append(song.Patch.SampleOffsets, SampleOffset{
				Start:      namedParams["start"],
				LoopStart:  namedParams["loopstart"],
				LoopLength: namedParams["looplength"]})
		}
		if strings.HasPrefix(word, "SU_") {
			unittype := strings.ToLower(word[3:])
			unit := Unit{Type: unittype, Parameters: namedParams}
			lastIndex := len(song.Patch.Instruments) - 1
			if lastIndex < 0 {
				return nil, fmt.Errorf("opcode %v before BEGIN_INSTRUMENT", word)
			}
			song.Patch.Instruments[lastIndex].Units = append(song.Patch.Instruments[lastIndex].Units, unit)
		}

	}
	return &song, nil
}

func FormatAsm(song *Song) (string, error) {
	paramorder := map[string][]string{
		"add":        []string{"stereo"},
		"addp":       []string{"stereo"},
		"pop":        []string{"stereo"},
		"loadnote":   []string{"stereo"},
		"mul":        []string{"stereo"},
		"mulp":       []string{"stereo"},
		"push":       []string{"stereo"},
		"xch":        []string{"stereo"},
		"distort":    []string{"stereo", "drive"},
		"hold":       []string{"stereo", "holdfreq"},
		"crush":      []string{"stereo", "resolution"},
		"gain":       []string{"stereo", "gain"},
		"invgain":    []string{"stereo", "invgain"},
		"filter":     []string{"stereo", "frequency", "resonance", "lowpass", "bandpass", "highpass", "negbandpass", "neghighpass"},
		"clip":       []string{"stereo"},
		"pan":        []string{"stereo", "panning"},
		"delay":      []string{"stereo", "pregain", "dry", "feedback", "damp", "delay", "count", "notetracking"},
		"compressor": []string{"stereo", "attack", "release", "invgain", "threshold", "ratio"},
		"speed":      []string{},
		"out":        []string{"stereo", "gain"},
		"outaux":     []string{"stereo", "outgain", "auxgain"},
		"aux":        []string{"stereo", "gain", "channel"},
		"send":       []string{"stereo", "amount", "voice", "unit", "port", "sendpop"},
		"envelope":   []string{"stereo", "attack", "decay", "sustain", "release", "gain"},
		"noise":      []string{"stereo", "shape", "gain"},
		"oscillator": []string{"stereo", "transpose", "detune", "phase", "color", "shape", "gain", "type", "lfo", "unison"},
		"loadval":    []string{"stereo", "value"},
		"receive":    []string{"stereo"},
		"in":         []string{"stereo", "channel"},
	}
	indentation := 0
	indent := func() string {
		return strings.Repeat(" ", indentation*4)
	}
	var b strings.Builder
	println := func(format string, params ...interface{}) {
		if len(format) > 0 {
			fmt.Fprintf(&b, "%v", indent())
			fmt.Fprintf(&b, format, params...)
		}
		fmt.Fprintf(&b, "\n")
	}
	align := func(table [][]string, format string) [][]string {
		var maxwidth []int
		// find the maximum width of each column
		for _, row := range table {
			for k, elem := range row {
				l := len(elem)
				if len(maxwidth) <= k {
					maxwidth = append(maxwidth, l)
				} else {
					if maxwidth[k] < l {
						maxwidth[k] = l
					}
				}
			}
		}
		// align each column, depending on the specified formatting
		for _, row := range table {
			for k, elem := range row {
				l := len(elem)
				var f byte
				if k >= len(format) {
					f = format[len(format)-1] // repeat the last format specifier for all remaining columns
				} else {
					f = format[k]
				}
				switch f {
				case 'n': // no alignment
					row[k] = elem
				case 'l': // left align
					row[k] = elem + strings.Repeat(" ", maxwidth[k]-l)
				case 'r': // right align
					row[k] = strings.Repeat(" ", maxwidth[k]-l) + elem
				}
			}
		}
		return table
	}
	printTable := func(table [][]string) {
		indentation++
		for _, row := range table {
			println("%v %v", row[0], strings.Join(row[1:], ","))
		}
		indentation--
	}
	// delay modulation is pretty much the only %define that the asm preprocessor cannot figure out
	// as the preprocessor has no clue if a SEND modulates a delay unit. So, unfortunately, for the
	// time being, we need to figure during export if INCLUDE_DELAY_MODULATION needs to be defined.
	delaymod := 0
	for i, instrument := range song.Patch.Instruments {
		for j, unit := range instrument.Units {
			if unit.Type == "send" {
				targetInstrument := i
				if unit.Parameters["voice"] > 0 {
					v, err := song.Patch.InstrumentForVoice(unit.Parameters["voice"] - 1)
					if err != nil {
						return "", fmt.Errorf("INSTRUMENT #%v / SEND #%v targets voice %v, which does not exist", i, j, unit.Parameters["voice"])
					}
					targetInstrument = v
				}
				if unit.Parameters["unit"] < 0 || unit.Parameters["unit"] >= len(song.Patch.Instruments[targetInstrument].Units) {
					return "", fmt.Errorf("INSTRUMENT #%v / SEND #%v target unit %v out of range", i, j, unit.Parameters["unit"])
				}
				if song.Patch.Instruments[targetInstrument].Units[unit.Parameters["unit"]].Type == "delay" && unit.Parameters["port"] == 5 {
					delaymod = 1
				}
			}
		}
	}
	// The actual printing starts here
	output_16bit := 0
	if song.Output16Bit {
		output_16bit = 1
	}
	println("%%include \"sointu/header.inc\"\n")
	println("BEGIN_SONG BPM(%v),OUTPUT_16BIT(%v),CLIP_OUTPUT(0),DELAY_MODULATION(%v),HOLD(%v)\n", song.BPM, output_16bit, delaymod, song.Hold)
	var patternTable [][]string
	for _, pattern := range song.Patterns {
		row := []string{"PATTERN"}
		for _, v := range pattern {
			row = append(row, strconv.Itoa(int(v)))
		}
		patternTable = append(patternTable, row)
	}
	println("BEGIN_PATTERNS")
	printTable(align(patternTable, "lr"))
	println("END_PATTERNS\n")
	var trackTable [][]string
	for _, track := range song.Tracks {
		row := []string{"TRACK", fmt.Sprintf("VOICES(%d)", track.NumVoices)}
		for _, v := range track.Sequence {
			row = append(row, strconv.Itoa(int(v)))
		}
		trackTable = append(trackTable, row)
	}
	println("BEGIN_TRACKS")
	printTable(align(trackTable, "lr"))
	println("END_TRACKS\n")
	println("BEGIN_PATCH")
	indentation++
	for _, instrument := range song.Patch.Instruments {
		var instrTable [][]string
		for _, unit := range instrument.Units {
			row := []string{fmt.Sprintf("SU_%v", strings.ToUpper(unit.Type))}
			for _, parname := range paramorder[unit.Type] {
				if v, ok := unit.Parameters[parname]; ok {
					row = append(row, fmt.Sprintf("%v(%v)", strings.ToUpper(parname), strconv.Itoa(int(v))))
				} else {
					return "", fmt.Errorf("The parameter map for unit %v does not contain %v, even though it should", unit.Type, parname)
				}
			}
			instrTable = append(instrTable, row)
		}
		println("BEGIN_INSTRUMENT VOICES(%d)", instrument.NumVoices)
		printTable(align(instrTable, "ln"))
		println("END_INSTRUMENT")
	}
	indentation--
	println("END_PATCH\n")
	if len(song.Patch.DelayTimes) > 0 {
		var delStrTable [][]string
		for _, v := range song.Patch.DelayTimes {
			row := []string{"DELTIME", strconv.Itoa(int(v))}
			delStrTable = append(delStrTable, row)
		}
		println("BEGIN_DELTIMES")
		printTable(align(delStrTable, "lr"))
		println("END_DELTIMES\n")
	}
	if len(song.Patch.SampleOffsets) > 0 {
		var samStrTable [][]string
		for _, v := range song.Patch.SampleOffsets {
			samStrTable = append(samStrTable, []string{
				"SAMPLE_OFFSET",
				fmt.Sprintf("START(%d)", v.Start),
				fmt.Sprintf("LOOPSTART(%d)", v.LoopStart),
				fmt.Sprintf("LOOPLENGTH(%d)", v.LoopLength),
			})
		}
		println("BEGIN_SAMPLE_OFFSETS")
		printTable(align(samStrTable, "r"))
		println("END_SAMPLE_OFFSETS\n")
	}
	println("END_SONG")
	ret := b.String()
	return ret, nil
}

func CHeader(song *Song, maxSamples int) string {
	template :=
		`// auto-generated by Sointu, editing not recommended
#ifndef SU_RENDER_H
#define SU_RENDER_H

#define SU_MAX_SAMPLES     %v
#define SU_BUFFER_LENGTH   (SU_MAX_SAMPLES*2)

#define SU_SAMPLE_RATE     44100
#define SU_BPM             %v
#define SU_PATTERN_SIZE    %v
#define SU_MAX_PATTERNS    %v
#define SU_TOTAL_ROWS      (SU_MAX_PATTERNS*SU_PATTERN_SIZE)
#define SU_SAMPLES_PER_ROW (SU_SAMPLE_RATE*4*60/(SU_BPM*16))

#include <stdint.h>
#if UINTPTR_MAX == 0xffffffff
    #if defined(__clang__) || defined(__GNUC__)
        #define SU_CALLCONV __attribute__ ((stdcall))
    #elif defined(_WIN32)
        #define SU_CALLCONV __stdcall
    #endif
#else
    #define SU_CALLCONV
#endif

typedef %v SUsample;
#define SU_SAMPLE_RANGE %v

#ifdef __cplusplus
extern "C" {
#endif

void SU_CALLCONV su_render_song(SUsample *buffer);
%v
#ifdef __cplusplus
}
#endif

#endif
`
	maxSamplesText := "SU_TOTAL_ROWS*SU_SAMPLES_PER_ROW"
	if maxSamples > 0 {
		maxSamplesText = fmt.Sprintf("%v", maxSamples)
	}
	sampleType := "float"
	sampleRange := "1.0f"
	if song.Output16Bit {
		sampleType = "short"
		sampleRange = "32768"
	}
	defineGmdls := ""
	for _, instr := range song.Patch.Instruments {
		for _, unit := range instr.Units {
			if unit.Type == "oscillator" && unit.Parameters["type"] == Sample {
				defineGmdls = "\n#define SU_LOAD_GMDLS\nvoid SU_CALLCONV su_load_gmdls(void);"
				break
			}
		}
	}
	header := fmt.Sprintf(template, maxSamplesText, song.BPM, song.PatternRows(), song.SequenceLength(), sampleType, sampleRange, defineGmdls)
	return header
}