package wav

import "core:fmt"
import "core:math"
import "core:strings"
import "core:strconv"
import "core:os"
import "xml"

Wav :: struct {
	// Basic data
	path : string,
	format : Audio_Format,
	channels : int,
	sample_rate : int,
	bit_depth :  int,
	reported_size : u32,
	
	// Internals
	handle : os.Handle,
	
	// Metadata
	date : Date,
	channel_names : []string,
	samples_since_midnight: u64,
	timecode : Timecode, // Derived from samples_since_midnight
	tc_framerate : f32,
	tc_dropframe : bool,
	ubits : [8]u8,
	take : int,
	project : string,
	scene : string,
	note : string,
	tape : string,
	circled : bool,
}
Audio_Format :: enum {
	INT = 1,
	FLOAT = 3,
}
Timecode :: struct {
	hour   : u8,
	minute : u8,
	second : u8,
	frame  : f32,
}
Date :: struct {
	year, month, day : int,
}

VERBOSE :: false
BUFFER_SIZE :: 1<<15

main :: proc() {
	// Test
	enok, enok_ok := read("test/WAVs/ENOKS-BIRHTDAYT02.WAV", context.temp_allocator)
	when VERBOSE do fmt.printf("\n\nenok = %#v\n\n", enok)
	prins, prins_ok := read("test/WAVs/KRONPRINS01T01.wav", context.temp_allocator)
	when VERBOSE do fmt.printf("\n\nprins = %#v\n\n", prins)
	f8, f8_ok := read("test/WAVs/F8-SL098-T001.WAV", context.temp_allocator)
	when VERBOSE do fmt.printf("\n\nf8 = %#v\n\n", f8)
}

/*
Reads in the wav file metadata, without loading the sound data into ram.
*/
read :: proc(path : string, allocator:=context.allocator) -> (Wav, bool) #optional_ok {
	file : Wav
	file.path = path
	
	load_err : os.Error
	file.handle, load_err = os.open(path)
	defer os.close(file.handle)
	defer file.handle = 0
	if load_err != os.General_Error.None {
		fmt.eprintln("ERROR %v: Unable to load file \"%v\"", load_err, path)
		return {}, false
	}
	
	
	temp_buf := new([BUFFER_SIZE]u8)[:]
	temp_bext : []u8
	temp_ixml : string
	defer delete(temp_buf)
	
	os.read(file.handle, temp_buf)
	
	head : int = 0
	
	// RIFF header
	when VERBOSE do fmt.println(string(temp_buf[0:4]))
	if string(temp_buf[0:4]) != "RIFF" do return {}, false
	head += 4
	
	// Size
	file.reported_size = read_little_endian_u32(temp_buf[head:head+4])
	when VERBOSE do fmt.println("Reported size:", file.reported_size)
	head += 4
	
	// Confirming again that this is a wave file
	when VERBOSE do fmt.println(string(temp_buf[head:head+4]))
	if string(temp_buf[head:head+4]) != "WAVE" do return {}, false
	head += 4
	
	when VERBOSE do fmt.println("\nChunks:\n")
	
	// Looping through chunks
	null_chunks := 0
	for _ in 0..<BUFFER_SIZE {
		chunk_id_raw := temp_buf[head:head+4]
		chunk_id := string(chunk_id_raw)
		head += 4
		chunk_size := int(read_little_endian_u32(temp_buf[head:head+4]))
		head += 4
		when VERBOSE do fmt.println(chunk_id, chunk_size,"\n-------------------------------------")
		data_reached := false
		next_chunk_start := head + chunk_size
		
		if head+chunk_size < BUFFER_SIZE {
			print_data : string
			data_end := head+chunk_size
			read_end := min(head+15000, data_end)
			switch chunk_id {
				case "iXML":
					temp_ixml = string(temp_buf[head:data_end])
					//print_data = temp_ixml
					null_chunks = 0
				case "bext":
					temp_bext = temp_buf[head:data_end]
					//print_data = string(temp_bext)
					null_chunks = 0
				case "fmt ":
					file.format = Audio_Format(read_little_endian_u16(temp_buf[head:]))
					when VERBOSE do fmt.println("Format:", file.format)
					head += 2
					file.channels = int(read_little_endian_u16(temp_buf[head:]))
					when VERBOSE do fmt.println("Channels:", file.channels)
					head += 2
					file.sample_rate = int(read_little_endian_u32(temp_buf[head:]))
					when VERBOSE do fmt.println("Sample rate:", file.sample_rate)
					head += 4
					
					// Skipping byte rate and block align.
					// These two legacy fields are only ever redundant or wrong,
					// and are implied by the other fields.
					head += 4 + 2
					
					file.bit_depth = int(read_little_endian_u16(temp_buf[head:]))
					when VERBOSE do fmt.println("Bit depth:", file.bit_depth)
					head += 2
					head = data_end
					null_chunks = 0
				case "data":
					data_reached = true
				case "\x00\x00\x00\x00":
					if chunk_size == 0 {
						null_chunks += 1
					}
			}
			when VERBOSE do fmt.println(print_data, "\n")
		} else {
			when VERBOSE do fmt.println("End of buffer reached.")
			break
		}
		
		
		head = next_chunk_start
		
		if null_chunks > 3 {
			when VERBOSE do fmt.println("Got more than 3 null chunks in a row. Quitting parse.")
			break
		}
		if data_reached {
			when VERBOSE do fmt.println("Data reached.")
		} 
	}
	
	file.channel_names = make([]string, file.channels, allocator=allocator)
	
	
	
	// iXML Parsing
	if temp_ixml != "" {
		
		// Stripping null padding
		end := len(temp_ixml) - 1
		for end >= 0 && temp_ixml[end] == 0 {
			end -= 1
		}
		temp_ixml = temp_ixml[:end]
		
		
		naming_channel := 0
		/*
		interleave_set is here because we don't want to overwrite naming_channel
		with a number from CHANNEL_INDEX, if we've already set it with INTERLEAVE_INDEX.
		INTERLEAVE_INDEX is the number that actually tells you which channel the name
		belongs to. CHANNEL_INDEX is to be treated as a backup.
		*/
		interleave_set := false
		
		xml_recurse :: proc(doc: ^xml.Document, element_id: xml.Element_ID, file: ^Wav, naming_channel: ^int, interleave_set: ^bool, allocator:=context.allocator, indent := 0) {
			
			naming_channel := naming_channel
			interleave_set := interleave_set
			
			
			tab :: proc(indent: int) {
				for _ in 0..=indent {
					fmt.printf("\t")
				}
			}
		
			when VERBOSE do fmt.printf("\n")
			when VERBOSE do tab(indent)
		
			element := doc.elements[element_id]
			
			if element.kind == .Element {
				when VERBOSE do fmt.printf("<%v>", element.ident)
				
				if len(element.value) > 0 {
					value := element.value[0]
					switch element.ident {
						case "TRACK":
							interleave_set^ = false
						case "CHANNEL_INDEX":
							if !interleave_set^ {
								switch v in value {
									case string:
										naming_channel^, _ = strconv.parse_int(v)
									case u32:
										naming_channel^ = int(v)
								}
							}
							naming_channel^ -= 1
						case "INTERLEAVE_INDEX":
							interleave_set^ = true
							switch v in value {
								case string:
									naming_channel^, _ = strconv.parse_int(v)
								case u32:
									naming_channel^ = int(v)
							}
							naming_channel^ -= 1
						case "NAME":
							#partial switch v in value {
								case string:
									file.channel_names[naming_channel^] = strings.clone(v, allocator=allocator)
							}
						case "UBITS":
							#partial switch v in value {
								case string:
									for r, i in v {
										file.ubits[i] = u8(r) - u8('0')
									}
							}
						case "TAKE":
							#partial switch v in value {
								case string:
									file.take, _ = strconv.parse_int(v)
							}
						case "SCENE":
							#partial switch v in value {
								case string:
									file.scene = strings.clone(v, allocator=allocator)
							}
						case "PROJECT":
							#partial switch v in value {
								case string:
									file.project = strings.clone(v, allocator=allocator)
							}
						case "TAPE":
							#partial switch v in value {
								case string:
									file.tape = strings.clone(v, allocator=allocator)
							}
						case "CIRCLED":
							#partial switch v in value {
								case string:
									file.circled = v == "TRUE"
							}
						case "TIMECODE_FLAG":
							#partial switch v in value {
								case string:
									file.tc_dropframe = v != "NDF"
							}
						case "TIMECODE_RATE":
							#partial switch v in value {
								case string:
									end : int
									for r, i in v {
										if r == '/' {
											end = i
											break
										}
									}
									file.tc_framerate, _ = strconv.parse_f32(v[:end])
							}
						case "NOTE":
							#partial switch v in value {
								case string:
									if v != "" {
										file.note = strings.clone(v, allocator=allocator)
									}
							}
					}
				}
				
				for value in element.value {
					switch v in value {
						case string:
							when VERBOSE do fmt.printf(": %v", v)
						case xml.Element_ID:
							xml_recurse(doc, v, file, naming_channel, interleave_set, allocator, indent + 1)
					}
				}
		
				for attr in element.attribs {
					when VERBOSE do tab(indent + 1)
					when VERBOSE do fmt.printf("[Attr] %v: %v\n", attr.key, attr.val)
				}
			} else if element.kind == .Comment {
				when VERBOSE do fmt.printf("[COMMENT] %v\n", element.value)
			}
		
			return
		}
		
		
		parsed_ixml : ^xml.Document
		parsed_ixml, _ = xml.parse(temp_ixml, xml.Options{
			flags={.Ignore_Unsupported},
			expected_doctype = "",
		})
		xml_recurse(parsed_ixml, 0, &file, &naming_channel, &interleave_set, allocator)
	}
	
	// bext parsing
	if len(temp_bext) > 0 {
		
		// Stripping null padding
		end := len(temp_bext) - 1
		for end >= 0 && temp_bext[end] == 0 {
			end -= 1
		}
		temp_bext = temp_bext[:end]
		
		naming_channel := 0
		
		description := string(temp_bext[:256])
		for line in strings.split_lines(description) {
			
			if file.channel_names[naming_channel] == "" &&
			  (strings.starts_with(line, "sTRK") || strings.starts_with(line, "zTRK")) {
				eq_index := strings.index(line, "=")
				file.channel_names[naming_channel] = strings.clone(line[eq_index+1:], allocator=allocator)
				naming_channel += 1
			}
			if strings.starts_with(line[1:], "TAKE=")      {
				file.take, _ = strconv.parse_int(line[6:])
			}
			if strings.starts_with(line[1:], "CIRCLED=")   {
				file.circled = line[9:] == "TRUE"
			}
			if strings.starts_with(line[1:], "SPEED=")     {
				value := line[7:]
				num_end : int
				type_start : int
				for r, i in value {
					if !strings.contains_rune("1234567890.", r) && num_end == 0 {
						num_end = i
					}
					if r=='N' || r=='D' {
						type_start = i
						break
					}
				}
				file.tc_framerate, _ = strconv.parse_f32(value[:num_end])
				file.tc_dropframe = value[type_start:] != "ND"
				
			}
			// Only if ixml doesn't exist, so we don't allocate the note string twice.
			if file.note == "" {
				if strings.starts_with(line[1:], "NOTE=")  {
					v := line[6:]
					if v != "" {
						file.note = strings.clone(v, allocator=allocator)
					}
				}
			}
		}
		head := 0
		when VERBOSE do fmt.printf("Description: \n%v\n", string(temp_bext[head:256]))
		head += 256
		when VERBOSE do fmt.printf("Originator: %v\n", string(temp_bext[head:head+32]))
		head += 32
		when VERBOSE do fmt.printf("Originator Reference: %v\n", string(temp_bext[head:head+32]))
		head += 32
		date := string(temp_bext[head:head+10])
		when VERBOSE do fmt.printf("Origination Date: %v\n", date)
		date_splits := strings.split(date, "-")
		file.date.year, _ = strconv.parse_int(date_splits[0])
		file.date.month, _ = strconv.parse_int(date_splits[1])
		file.date.day, _ = strconv.parse_int(date_splits[2])
		delete(date_splits)
		head += 10
		when VERBOSE do fmt.printf("Origination Time: %v\n", string(temp_bext[head:head+8]))
		head += 8
		
		file.samples_since_midnight = read_little_endian_u64(temp_bext[head:head+8])
		
		seconds_since_midnight := file.samples_since_midnight / u64(file.sample_rate)
		file.timecode.hour   = u8( seconds_since_midnight / 3600)
		file.timecode.minute = u8((seconds_since_midnight % 3600) / 60)
		file.timecode.second = u8( seconds_since_midnight % 60)
		file.timecode.frame  = f32( f64(file.samples_since_midnight % u64(file.sample_rate)  ) * f64(file.tc_framerate) / f64(file.sample_rate))
		when VERBOSE do fmt.printf("Time Reference: %v (Samples since midnight, source of timecode)\n", file.samples_since_midnight)
		when VERBOSE do fmt.printf("                %v seconds + %v samples\n", seconds_since_midnight, file.samples_since_midnight % u64(file.sample_rate))
		head += 8
		
		when VERBOSE do fmt.printf("Version: %v\n", read_little_endian_u16(temp_bext[head:head+2]))
		head += 2
		when VERBOSE do fmt.printf("UMID Skipped.\n")
		head += 64
		when VERBOSE do fmt.printf("Skipped reserved nothingness.\n")
		head += 190
		when VERBOSE do fmt.printf("Coding history:\n%v\n", string(temp_bext[head:]))
	}
	when VERBOSE do fmt.println()
	
	// just here to make some printing prettier
	temp_bext = nil
	
	temp_buf = nil
	return file, true
}



read_little_endian_u64 :: proc(x : []u8) -> u64 {
	return u64(x[0])       |
	       u64(x[1]) <<  8 |
	       u64(x[2]) << 16 |
	       u64(x[3]) << 24 |
	       u64(x[4]) << 32 |
	       u64(x[5]) << 40 |
	       u64(x[6]) << 48 |
	       u64(x[7]) << 56
}

read_little_endian_u32 :: proc(x : []u8) -> u32 {
	return u32(x[0])       |
	       u32(x[1]) <<  8 |
	       u32(x[2]) << 16 |
	       u32(x[3]) << 24
}

read_little_endian_u16 :: proc(x : []u8) -> u16 {
	return u16(x[0])       |
	       u16(x[1]) <<  8
}