use std::{collections::HashMap, path::PathBuf, str::FromStr as _};

use anyhow::{Context as _, Result};
use base58::ToBase58 as _;
use key_protocol::key_protocol_core::NSSAUserData;
use nssa::Account;
use nssa_core::account::Nonce;
use rand::{RngCore as _, rngs::OsRng};
use serde::Serialize;
use testnet_initial_state::{PrivateAccountPrivateInitialData, PublicAccountPrivateInitialData};

use crate::{
    HOME_DIR_ENV_VAR,
    config::{
        InitialAccountData, Label, PersistentAccountDataPrivate, PersistentAccountDataPublic,
        PersistentStorage,
    },
};

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum AccountPrivacyKind {
    Public,
    Private,
}

/// Human-readable representation of an account.
#[derive(Serialize)]
pub(crate) struct HumanReadableAccount {
    balance: u128,
    program_owner: String,
    data: String,
    nonce: u128,
}

impl From<Account> for HumanReadableAccount {
    fn from(account: Account) -> Self {
        let program_owner = account
            .program_owner
            .iter()
            .flat_map(|n| n.to_le_bytes())
            .collect::<Vec<u8>>()
            .to_base58();
        let data = hex::encode(account.data);
        Self {
            balance: account.balance,
            program_owner,
            data,
            nonce: account.nonce.0,
        }
    }
}

/// Resolve an account id-or-label pair to a `Privacy/id` string.
///
/// Exactly one of `id` or `label` must be `Some`. If `id` is provided it is
/// returned as-is; if `label` is provided it is resolved via
/// [`resolve_account_label`]. Any other combination returns an error.
pub fn resolve_id_or_label(
    id: Option<String>,
    label: Option<String>,
    labels: &HashMap<String, Label>,
    user_data: &NSSAUserData,
) -> Result<String> {
    match (id, label) {
        (Some(id), None) => Ok(id),
        (None, Some(label)) => resolve_account_label(&label, labels, user_data),
        _ => anyhow::bail!("provide exactly one of account id or account label"),
    }
}

/// Resolve an account label to its full `Privacy/id` string representation.
///
/// Looks up the label in the labels map and determines whether the account is
/// public or private by checking the user data key trees.
pub fn resolve_account_label(
    label: &str,
    labels: &HashMap<String, Label>,
    user_data: &NSSAUserData,
) -> Result<String> {
    let account_id_str = labels
        .iter()
        .find(|(_, l)| l.to_string() == label)
        .map(|(k, _)| k.clone())
        .ok_or_else(|| anyhow::anyhow!("No account found with label '{label}'"))?;

    let account_id: nssa::AccountId = account_id_str.parse()?;

    let privacy = if user_data
        .public_key_tree
        .account_id_map
        .contains_key(&account_id)
        || user_data
            .default_pub_account_signing_keys
            .contains_key(&account_id)
    {
        "Public"
    } else if user_data
        .private_key_tree
        .account_id_map
        .contains_key(&account_id)
        || user_data
            .default_user_private_accounts
            .contains_key(&account_id)
    {
        "Private"
    } else {
        anyhow::bail!("Account with label '{label}' not found in wallet");
    };

    Ok(format!("{privacy}/{account_id_str}"))
}

/// Get home dir for wallet. Env var `NSSA_WALLET_HOME_DIR` must be set before execution to succeed.
fn get_home_nssa_var() -> Result<PathBuf> {
    Ok(PathBuf::from_str(&std::env::var(HOME_DIR_ENV_VAR)?)?)
}

/// Get home dir for wallet. Env var `HOME` must be set before execution to succeed.
fn get_home_default_path() -> Result<PathBuf> {
    std::env::home_dir()
        .map(|path| path.join(".nssa").join("wallet"))
        .context("Failed to get HOME")
}

/// Get home dir for wallet.
pub fn get_home() -> Result<PathBuf> {
    get_home_nssa_var().or_else(|_| get_home_default_path())
}

/// Fetch config path from default home.
pub fn fetch_config_path() -> Result<PathBuf> {
    let home = get_home()?;
    let config_path = home.join("wallet_config.json");
    Ok(config_path)
}

/// Fetch path to data storage from default home.
///
/// File must be created through setup beforehand.
pub fn fetch_persistent_storage_path() -> Result<PathBuf> {
    let home = get_home()?;
    let accs_path = home.join("storage.json");
    Ok(accs_path)
}

/// Produces data for storage.
#[must_use]
pub fn produce_data_for_storage(
    user_data: &NSSAUserData,
    last_synced_block: u64,
    labels: HashMap<String, Label>,
) -> PersistentStorage {
    let mut vec_for_storage = vec![];

    for (account_id, key) in &user_data.public_key_tree.account_id_map {
        if let Some(data) = user_data.public_key_tree.key_map.get(key) {
            vec_for_storage.push(
                PersistentAccountDataPublic {
                    account_id: *account_id,
                    chain_index: key.clone(),
                    data: data.clone(),
                }
                .into(),
            );
        }
    }

    for (chain_index, node) in &user_data.private_key_tree.key_map {
        let identifiers = node.value.1.iter().map(|(id, _)| *id).collect();
        vec_for_storage.push(
            PersistentAccountDataPrivate {
                identifiers,
                chain_index: chain_index.clone(),
                data: node.clone(),
            }
            .into(),
        );
    }

    for (account_id, key) in &user_data.default_pub_account_signing_keys {
        vec_for_storage.push(
            InitialAccountData::Public(PublicAccountPrivateInitialData {
                account_id: *account_id,
                pub_sign_key: key.clone(),
            })
            .into(),
        );
    }

    for entry in user_data.default_user_private_accounts.values() {
        for (identifier, account) in &entry.accounts {
            vec_for_storage.push(
                InitialAccountData::Private(Box::new(PrivateAccountPrivateInitialData {
                    account: account.clone(),
                    key_chain: entry.key_chain.clone(),
                    identifier: *identifier,
                }))
                .into(),
            );
        }
    }

    PersistentStorage {
        accounts: vec_for_storage,
        last_synced_block,
        labels,
    }
}

#[expect(dead_code, reason = "Maybe used later")]
pub(crate) fn produce_random_nonces(size: usize) -> Vec<Nonce> {
    let mut result = vec![[0; 16]; size];
    for bytes in &mut result {
        OsRng.fill_bytes(bytes);
    }
    result
        .into_iter()
        .map(|x| Nonce(u128::from_le_bytes(x)))
        .collect()
}

pub(crate) fn parse_addr_with_privacy_prefix(
    account_base58: &str,
) -> Result<(String, AccountPrivacyKind)> {
    if account_base58.starts_with("Public/") {
        Ok((
            account_base58.strip_prefix("Public/").unwrap().to_owned(),
            AccountPrivacyKind::Public,
        ))
    } else if account_base58.starts_with("Private/") {
        Ok((
            account_base58.strip_prefix("Private/").unwrap().to_owned(),
            AccountPrivacyKind::Private,
        ))
    } else {
        anyhow::bail!("Unsupported privacy kind, available variants is Public/ and Private/");
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn addr_parse_with_privacy() {
        let addr_base58 = "Public/BLgCRDXYdQPMMWVHYRFGQZbgeHx9frkipa8GtpG2Syqy";
        let (_, addr_kind) = parse_addr_with_privacy_prefix(addr_base58).unwrap();

        assert_eq!(addr_kind, AccountPrivacyKind::Public);

        let addr_base58 = "Private/BLgCRDXYdQPMMWVHYRFGQZbgeHx9frkipa8GtpG2Syqy";
        let (_, addr_kind) = parse_addr_with_privacy_prefix(addr_base58).unwrap();

        assert_eq!(addr_kind, AccountPrivacyKind::Private);

        let addr_base58 = "asdsada/BLgCRDXYdQPMMWVHYRFGQZbgeHx9frkipa8GtpG2Syqy";
        assert!(parse_addr_with_privacy_prefix(addr_base58).is_err());
    }
}