use std::ffi::OsStr;
use std::fs::File;
use std::io::BufReader;
use std::path::Path;
use std::{fs, io};

use image::ImageError;
use rqrr::DeQRError;

use crate::shared_secret::data_block::common::SharedSecretConfig;
use crate::shared_secret::data_block::shared_secret_data_block::SharedSecretBlock;
use crate::shared_secret::shared_secret::{
    PlainText, RecoveryError, SharedSecret, SharedSecretEncryption, UserShareDto,
};
use crate::RecoveryError::EmptyInput;

pub mod crypto;
pub mod sdk;
pub mod shared_secret;

#[derive(Debug, thiserror::Error)]
pub enum RecoveryOperationError {
    #[error(transparent)]
    LoaderError(#[from] SharesLoaderError),
    #[error(transparent)]
    RecoveryFromSharesError(#[from] RecoveryError),
}

pub fn recover() -> Result<PlainText, RecoveryOperationError> {
    let users_shares = load_users_shares()?;
    let recovered = recover_from_shares(users_shares)?;
    Ok(recovered)
}

pub fn recover_from_shares(users_shares: Vec<UserShareDto>) -> Result<PlainText, RecoveryError> {
    let mut secret_blocks: Vec<SharedSecretBlock> = vec![];

    if users_shares[0].share_blocks.is_empty() {
        return Err(EmptyInput("Empty shares list. Nothing to recover".to_string()));
    }

    let blocks_num: usize = users_shares[0].share_blocks.len();

    for block_index in 0..blocks_num {
        let mut encrypted_data_blocks = vec![];

        for user_share in users_shares.iter() {
            let encrypted_data_block = user_share.get_encrypted_data_block(block_index);
            encrypted_data_blocks.push(encrypted_data_block);
        }

        let curr_block = &users_shares[0].share_blocks[block_index];
        let secret_block = SharedSecretBlock {
            config: curr_block.config,
            meta_data: curr_block.meta_data.clone(),
            shares: encrypted_data_blocks,
        };

        secret_blocks.push(secret_block);
    }

    let secret = SharedSecret { secret_blocks };

    secret.recover()
}

#[derive(Debug, thiserror::Error)]
pub enum SharesLoaderError {
    #[error(transparent)]
    FileSystemError(#[from] io::Error),
    #[error(transparent)]
    DeserializationError(#[from] serde_json::error::Error),
}

fn load_users_shares() -> Result<Vec<UserShareDto>, SharesLoaderError> {
    //read json files
    let shares = fs::read_dir("secrets")?;

    let mut users_shares_dto: Vec<UserShareDto> = vec![];
    for secret_share_file in shares {
        let file_path = secret_share_file?.path();

        let maybe_ext = file_path.extension().and_then(OsStr::to_str);

        if let Some(ext) = maybe_ext {
            if ext.eq("json") {
                // Open the file in read-only mode with buffer.
                let file = File::open(file_path)?;
                let reader = BufReader::new(file);

                // Read the JSON contents of the file as an instance of `User`.
                let secret_share: UserShareDto = serde_json::from_reader(reader)?;
                users_shares_dto.push(secret_share);
            }
        }
    }

    Ok(users_shares_dto)
}

#[derive(Debug, thiserror::Error)]
pub enum SplitError {
    #[error("Secrets directory can't be created")]
    SecretsDirectoryError {
        #[from]
        source: io::Error,
    },
    #[error("User secret share: invalid format (can't be serialized into json)")]
    UserShareJsonSerializationError {
        #[from]
        source: serde_json::Error,
    },
}

pub fn split(secret: String, config: SharedSecretConfig) -> Result<(), SplitError> {
    let plain_text = PlainText::from_str(secret);
    let shared_secret = SharedSecretEncryption::new(config, &plain_text);

    fs::create_dir_all("secrets")?;

    for share_index in 0..config.number_of_shares {
        let share: UserShareDto = shared_secret.get_share(share_index);
        let share_json = serde_json::to_string_pretty(&share)?;

        // Save the JSON structure into the output file
        fs::write(format!("secrets/shared-secret-{share_index}.json"), share_json.clone())?;

        //generate qr code
        generate_qr_code(
            share_json.as_str(),
            format!("secrets/shared-secret-{share_index}.png").as_str(),
        )
    }

    Ok(())
}

pub fn generate_qr_code(data: &str, path: &str) {
    use qrcode_generator::QrCodeEcc;

    qrcode_generator::to_png_to_file(data, QrCodeEcc::High, data.len(), path).unwrap();
}

#[derive(Debug, thiserror::Error)]
pub enum QrToJsonParserError {
    #[error(
        "Secrets directory has invalid structure. \
        Please check that 'secrets' dir exists and \
        contains json or qr files with password shares"
    )]
    SecretsDirectoryError {
        #[from]
        source: io::Error,
    },
    #[error("Image parsing error")]
    ImageParsingError {
        #[from]
        source: QrCodeParserError,
    },
}

pub fn convert_qr_images_to_json_files() -> Result<Vec<String>, QrToJsonParserError> {
    let shares = fs::read_dir("secrets")?;

    let mut shares_json: Vec<String> = vec![];

    let mut share_index = 0;
    for secret_share_file in shares {
        let file_path = secret_share_file?.path();

        let extension = file_path.extension().and_then(OsStr::to_str).unwrap();

        if !extension.eq("png") {
            continue;
        }

        let json_str = read_qr_code(file_path.as_path())?;
        fs::write(format!("secrets/shared-secret-{share_index}.json"), json_str.clone())?;

        shares_json.push(json_str.clone());

        share_index += 1;
    }

    Ok(shares_json)
}

#[derive(Debug, thiserror::Error)]
pub enum QrCodeParserError {
    #[error("Qr code parsing error")]
    ImageParsingError {
        #[from]
        source: ImageError,
    },
    #[error("Error decoding image")]
    ImageDecodingError {
        #[from]
        source: DeQRError,
    },
}

pub fn read_qr_code(path: &Path) -> Result<String, QrCodeParserError> {
    let img = image::open(path)?.to_luma8();
    // Prepare for detection
    let mut img = rqrr::PreparedImage::prepare(img);
    // Search for grids, without decoding
    let grids = img.detect_grids();
    assert_eq!(grids.len(), 1);
    // Decode the grid
    let (_, content) = grids[0].decode()?;
    Ok(content)
}