use std::fs::File;
use std::path::{Path, PathBuf};
use std::fs::{self, OpenOptions};
use std::io::{Write, Read, Cursor, Seek, SeekFrom};
use binrw::{BinRead, BinReaderExt};

use crate::keys;
use crate::utils::common;
use crate::utils::pana_dvd_crypto::{decrypt_data};
use crate::utils::aes::{decrypt_aes128_cbc_nopad};
use crate::utils::compression::{decompress_gzip};
use crate::utils::lzss::{decompress_lzss};

pub struct PanaDvdContext {
    matching_key: [u8; 8],
    base_hdr_size: u32,
    is_aes: bool,
    aes_key: Option<[u8; 16]>,
    aes_iv: Option<[u8; 16]>
}

#[derive(BinRead)]
struct AesHeaderFileEntry {
    offset: u32,
    size: u32,
}

struct FileEntry {
    offset: u32,
    base_offset: u32,
}

//checksums are mostly Adler32, but some very old files use Checksum32 instead.

#[derive(BinRead)]
struct ModuleEntry {
    #[br(count = 4)] name_bytes: Vec<u8>,
    #[br(count = 4)] version_bytes: Vec<u8>,
    _unk: u32,
    offset: u32,
    #[br(count = 8)] platform_bytes: Vec<u8>,
    _unk1: u16,
    #[br(count = 6)] id_bytes: Vec<u8>,
    size: u32,
    data_checksum: u32, //checksum of the entrys' DATA
    _unk2: u32,
    _entry_checksum: u32, //checksum of THIS header entry (all previous 44 bytes)
}
impl ModuleEntry {
    fn name(&self) -> String {
        common::string_from_bytes(&self.name_bytes)
    }
    fn version(&self) -> String {
        common::string_from_bytes(&self.version_bytes)
    }
    fn platform(&self) -> String {
        common::string_from_bytes(&self.platform_bytes)
    }
    fn id(&self) -> String {
        common::string_from_bytes(&self.id_bytes)
    }
    fn is_valid(&self) -> bool {
        self.name().is_ascii() && self.platform().is_ascii()
    }
}

#[derive(BinRead)]
struct MainListHeader {
    _checksum: u32, //checksum of the MAIN LIST
    _unk: u32, //seems to be always 1?
    list_size: u32,
    decompressed_part_size: u32,
    _unk2: u32,
}
impl MainListHeader {
    fn entry_count(&self) -> u32 {
        (&self.list_size - 20) / 8
    }
}

#[derive(BinRead)]
struct MainListEntry {
    size: u32,
    checksum: u32, //checksum of this MAIN entrys' data
}

#[derive(BinRead)]
struct MainEntryHeader {
    #[br(count = 14)] _header_string: Vec<u8>, //EXTRHEADDRV \x01\x00
    compression_type_byte: u16,
    decompressed_size: u32,
    _destination_address: u32,
    compressed_size: u32,
    _unk: u32,
    _footer_offset: u32,
    _base_address: u32,
    _checksum: u32, //unknown type of checksum
    _checksum_flag: u8,
    #[br(count = 19)] _unused: Vec<u8>,
}
impl MainEntryHeader {
    fn compression_type(&self) -> &str {
        if self.compression_type_byte == 0 {
            return "Uncompressed"
        } else if self.compression_type_byte == 1 {
            return "GZIP + LZSS"
        } else if self.compression_type_byte == 2 {
            return "LZSS"
        } else {
            return "Unknown"
        }
    }
}

static MAX_HEADER_SIZE: usize = 0x2000;

pub fn find_key<'a>(key_array: &'a [&'a str], data: &[u8], expected_magic: &[u8], magic_offset: usize) -> Result<Option<[u8; 8]>, Box<dyn std::error::Error>> {
    for key_hex in key_array {
        let key_bytes = hex::decode(key_hex)?;
        let key_array: [u8; 8] = key_bytes.as_slice().try_into()?;
        let decrypted = decrypt_data(data, &key_array);
     
        if decrypted[magic_offset..].starts_with(expected_magic) {
            return Ok(Some(key_array));
        }
    }
    Ok(None)
}

pub fn find_aes_key_pair<'a>(key_array: &'a [(&'a str, &'a str, &'a str)], data: &[u8], expected_magic: &[u8], magic_offset: usize) -> Result<Option<([u8; 16], [u8; 16], [u8; 8])>, Box<dyn std::error::Error>> {
    for (aes_key_hex, aes_iv_hex, cust_key_hex) in key_array {
        let aes_key: [u8; 16] = hex::decode(aes_key_hex)?.as_slice().try_into()?;
        let aes_iv: [u8; 16] = hex::decode(aes_iv_hex)?.as_slice().try_into()?;
        let aes_decrypted = decrypt_aes128_cbc_nopad(data, &aes_key, &aes_iv)?;

        let key_bytes = hex::decode(cust_key_hex)?;
        let key_array: [u8; 8] = key_bytes.as_slice().try_into()?;
        let decrypted = decrypt_data(&aes_decrypted, &key_array);
     
        if decrypted[magic_offset..].starts_with(expected_magic) {
            return Ok(Some((aes_key, aes_iv, key_array)));
        }
    }
    Ok(None)
}

pub fn is_pana_dvd_file(file: &File) -> Result<Option<PanaDvdContext>, Box<dyn std::error::Error>> {
    let header = common::read_file(&file, 0, 64)?;
    if let Some(matching_key) = find_key(&keys::PANA_DVD_KEYONLY, &header, b"PROG", 0)? {
        Ok(Some(PanaDvdContext {
            matching_key: matching_key,
            base_hdr_size: 0,
            is_aes: false,
            aes_key: None, 
            aes_iv: None,
        }))
    } else if header.starts_with(b"PANASONIC\x00\x00\x00") && let Some(matching_key) = find_key(&keys::PANA_DVD_KEYONLY, &header, b"PROG", 48)? {
        Ok(Some(PanaDvdContext {
            matching_key: matching_key,
            base_hdr_size: 48,
            is_aes: false,
            aes_key: None, 
            aes_iv: None,
        }))
    } else if let Some((aes_key, aes_iv, matching_key)) = find_aes_key_pair(&keys::PANA_DVD_AESPAIR, &header, b"PANASONIC", 32)? {
        Ok(Some(PanaDvdContext {
            matching_key: matching_key,
            base_hdr_size: 48,
            is_aes: true,
            aes_key: Some(aes_key), 
            aes_iv: Some(aes_iv),
        }))
    } else {
        Ok(None)
    }
}

pub fn extract_pana_dvd(mut file: &File, output_folder: &str, context: PanaDvdContext) -> Result<(), Box<dyn std::error::Error>> {
    let mut data = Vec::new();  // we need to load the entire file into memory so we can swap it with AES decrypted data if its AES encrypted
    file.read_to_end(&mut data)?;
    let mut file_reader = Cursor::new(data);

    let matching_key = context.matching_key;
    let mut file_entries: Vec<FileEntry> = Vec::new();

    if context.is_aes {
        let (aes_key, aes_iv) = (context.aes_key.unwrap(), context.aes_iv.unwrap());
        println!("Using key: {} + AES key: {}, IV: {}", hex::encode_upper(matching_key), hex::encode_upper(aes_key), hex::encode_upper(aes_iv));
        println!("Decrypting AES...\n");
        let aes_decrypted = decrypt_aes128_cbc_nopad(&file_reader.get_ref(), &aes_key, &aes_iv)?;
        file_reader = Cursor::new(aes_decrypted); //set the file reader to use AES decrypted stream

        //read file entries in extra header
        let file_table = common::read_exact(&mut file_reader, 48)?;
        let mut file_table_reader = Cursor::new(decrypt_data(&file_table, &matching_key));
        for _i in 0..4 {
            let file_entry: AesHeaderFileEntry = file_table_reader.read_le()?;
            if file_entry.size == 0 && file_entry.offset == 0 {
                break
            }
            file_entries.push(FileEntry { offset: file_entry.offset, base_offset: context.base_hdr_size });
        }

    } else {
        println!("Using key: {}", hex::encode_upper(matching_key));
        file_entries.push(FileEntry { offset: 0, base_offset: context.base_hdr_size });
    }

    if file_entries.len() == 1 {
        //only one file, standard extraction
        println!("File contains no extra sub-files...\n");
        extract_file(&mut file_reader, file_entries[0].offset as u64, file_entries[0].base_offset as u64, matching_key, output_folder)?;
    } else {
        println!("File contains {} sub-files...", file_entries.len());
        for (i, file_entry ) in file_entries.iter().enumerate() {
            println!("\nExtracting file {}/{} - Offset: {}, base: {}", i + 1, file_entries.len(), file_entry.offset, file_entry.base_offset);
            extract_file(&mut file_reader, file_entry.offset as u64, file_entry.base_offset as u64, matching_key, &format!("{}/file_{}", output_folder, i + 1))?;
        }
    }

    println!("\nExtraction finished!");

    Ok(())
}

fn extract_file(file_reader: &mut Cursor<Vec<u8>>, offset: u64, base_offset: u64, key: [u8; 8], output_folder: &str) -> Result<(), Box<dyn std::error::Error>> {
    file_reader.seek(SeekFrom::Start(offset + base_offset))?;
 
    let enc_header = common::read_exact(file_reader, MAX_HEADER_SIZE)?;
    let mut hdr_reader = Cursor::new(decrypt_data(&enc_header, &key));
    let mut modules: Vec<ModuleEntry> = Vec::new();

    for i in 0..100 {
        let entry: ModuleEntry = hdr_reader.read_le()?;
        if !entry.is_valid() {break};
        println!("Module {} - Name: {}, Version: {}, Platform: {}, ID: {}, Offset: {}, Size: {}",
                i + 1, entry.name(), entry.version(), entry.platform(), entry.id(), entry.offset, entry.size);
        if modules.iter().any(|m| m.name() == entry.name()){
            println!("- Duplicate module, skipping!");
            continue
        }
        modules.push(entry);
    }

    let mut mod_i = 0;
    for module in &modules {
        mod_i += 1;
        println!("\n({}/{}) - {}, Offset: {}, Size: {}, Checksum: {:#010x}",
                mod_i, modules.len(), module.name(), module.offset, module.size, module.data_checksum);

        let output_path = Path::new(&output_folder).join(format!("{}.bin", module.name()));

        let rel_offset: u64 = offset + module.offset as u64;
        file_reader.seek(SeekFrom::Start(rel_offset))?;

        if module.name() == "MAIN" {
            println!("Extracting MAIN...");
            extract_main(file_reader, key, output_path)?;
            continue
        }

        let data = common::read_exact(file_reader, module.size as usize)?;
        println!("- Decrypting...");
        let dec_data = decrypt_data(&data, &key);
        
        fs::create_dir_all(&output_folder)?;
        let mut out_file = OpenOptions::new().write(true).create(true).open(output_path)?;
        out_file.write_all(&dec_data)?;
        
        println!("-- Saved file!");
    }

    Ok(())
}

fn extract_main(file_reader: &mut Cursor<Vec<u8>>, key: [u8; 8], output_path: PathBuf) -> Result<(), Box<dyn std::error::Error>> {
    let main_list_hdr: MainListHeader = file_reader.read_le()?;
    println!("MAIN - Entry count: {}, Decompressed part size: {}", main_list_hdr.entry_count(), main_list_hdr.decompressed_part_size);
    assert!(main_list_hdr.entry_count() < 200, "Unreasonable MAIN entry count!");

    let mut main_entries: Vec<MainListEntry> = Vec::new();
    for i in 0..main_list_hdr.entry_count() {
        let main_entry: MainListEntry = file_reader.read_le()?;
        println!("- Entry {}/{} - Size: {}, Checksum: {:#010x}",
                i + 1, main_list_hdr.entry_count(), main_entry.size, main_entry.checksum);
        main_entries.push(main_entry);
    }

    let mut maine_i = 0;
    for entry in &main_entries {
        maine_i += 1;
        let mut data = common::read_exact(file_reader, entry.size as usize)?;
        let decrypt_size: usize = if main_list_hdr.decompressed_part_size == 0x2000000 {10240} /* old type */ else {5120};
        if entry.size > decrypt_size as u32 {
            //decrypt first and last 5kb
            let first_decrypted = decrypt_data(&data[..decrypt_size], &key);
            data[..decrypt_size].copy_from_slice(&first_decrypted);

            let last_decrypted = decrypt_data(&data[entry.size as usize - decrypt_size..], &key);
            data[entry.size as usize - decrypt_size..].copy_from_slice(&last_decrypted);
            //
        } else {
            let decrypted = decrypt_data(&data, &key);
            data.copy_from_slice(&decrypted);
        }
        
        let mut data_reader = Cursor::new(data);
        let header: MainEntryHeader = data_reader.read_le()?;
        println!("\nMAIN ({}/{}) - Compressed size: {}, Decompressed size: {}, Compression type: {}({})", 
                maine_i, main_entries.len(), header.compressed_size, header.decompressed_size, header.compression_type_byte, header.compression_type());
        let compressed_data = common::read_exact(&mut data_reader, header.compressed_size as usize)?;

        let decompressed_data;
        if header.compression_type_byte == 1 { //gzip + lzss
            println!("- (1/2) Decompressing GZIP...");
            let decompressed_gzip = decompress_gzip(&compressed_data)?;
            // the decompressed data has another header
            let mut decompressed_gzip_reader = Cursor::new(decompressed_gzip);
            let header: MainEntryHeader = decompressed_gzip_reader.read_le()?;
            println!("- (2/2) Decompressing LZSS... (Compressed size: {}, Decompressed size: {})", header.compressed_size, header.decompressed_size);
            let compressed_lzss = common::read_exact(&mut decompressed_gzip_reader, header.compressed_size as usize)?;
            decompressed_data = decompress_lzss(&compressed_lzss);
            assert!(decompressed_data.len() == header.decompressed_size as usize, "Decompressed size does not match size in header, decompression failed!");

        } else if header.compression_type_byte == 2 { //only lzss
            println!("- Decompressing LZSS...");
            decompressed_data = decompress_lzss(&compressed_data);
            assert!(decompressed_data.len() == header.decompressed_size as usize, "Decompressed size does not match size in header, decompression failed!");

        } else if header.compression_type_byte == 0 { //no compression. havent encountered one yet
            decompressed_data = compressed_data;
            
        } else {
            println!("- Unknown compression method!");
            decompressed_data = compressed_data;
        }

        let mut out_file = OpenOptions::new().append(true).create(true).open(&output_path)?;
        out_file.write_all(&decompressed_data)?;
        
        println!("-- Saved to MAIN!");
    }

    Ok(())
}