use core::ops::Index;
use core::str::FromStr;
use beancount_importers_framework::error::ImporterBuilderError;
use beancount_importers_framework::error::UninitializedFieldSnafu;
use beancount_types::common_keys;
use beancount_types::Account;
use beancount_types::AccountTemplate;
use beancount_types::Amount;
use beancount_types::Commodity;
use beancount_types::CostBasis;
use beancount_types::Directive;
use beancount_types::Link;
use beancount_types::Price;
use beancount_types::Seg;
use beancount_types::Transaction;
use derive_builder::Builder;
use miette::Diagnostic;
use miette::IntoDiagnostic;
use serde::Deserialize;
use snafu::Backtrace;
use snafu::OptionExt as _;
use snafu::Snafu;
use tap::Tap as _;
use time::macros::format_description;
use time::Date;
#[derive(Builder, Clone, Debug, Deserialize)]
#[builder(
    build_fn(error = "ImporterBuilderError", skip),
    name = "ImporterBuilder",
    setter(into),
    try_setter
)]
pub struct Config {
    pub account_template: AccountTemplate<TemplateSelector>,
    pub capital_gains_template: AccountTemplate<TemplateSelector>,
    pub payee: String,
    pub reference_account: AccountTemplate<TemplateSelector>,
}
#[derive(Debug, Diagnostic, Snafu)]
pub enum Error {}
#[derive(Debug, Deserialize)]
pub struct Importer {
    #[serde(flatten)]
    config: Config,
    #[serde(default = "csv::Importer::semicolon_delimited", skip_deserializing)]
    importer: csv::Importer,
}
impl Importer {
    const NAME: &str = "bw-bank/portfolio-transactions";
    pub fn builder() -> ImporterBuilder {
        ImporterBuilder::default()
    }
    pub fn new(config: Config) -> Self {
        let importer = csv::Importer::semicolon_delimited();
        Self { config, importer }
    }
}
impl beancount_importers_framework::ImporterProtocol for Importer {
    type Error = miette::Report;
    fn account(&self, _file: &camino::Utf8Path) -> Result<Account, Self::Error> {
        Ok(self.config.account_template.base().to_owned())
    }
    fn date(&self, file: &camino::Utf8Path) -> Option<Result<Date, Self::Error>> {
        self.importer
            .date(file, self)
            .map(|result| result.map_err(Self::Error::from))
    }
    fn extract(
        &self,
        file: &camino::Utf8Path,
        existing: &[Directive],
    ) -> Result<Vec<Directive>, Self::Error> {
        self.importer
            .extract(file, existing, self)
            .map_err(Self::Error::from)
    }
    fn filename(&self, _file: &camino::Utf8Path) -> Option<Result<String, Self::Error>> {
        Some(Ok(String::from("transactions.csv")))
    }
    fn identify(&self, file: &camino::Utf8Path) -> Result<bool, Self::Error> {
        const EXPECTED_HEADERS: &[&str] = &[
            "Isin",
            "Wertpapierbezeichnung",
            "Datum",
            "Ordernummer",
            "Geschäftsart",
            "Stück",
            "Einheit",
            "Kurs",
            "Devisenkurs",
            "Kurswert",
        ];
        self.importer
            .identify(file, EXPECTED_HEADERS)
            .into_diagnostic()
    }
    fn name(&self) -> &'static str {
        Self::NAME
    }
    fn typetag_deserialize(&self) {}
}
impl csv::RecordImporter for Importer {
    type Error = Error;
    fn date(&self, record: &csv::Record) -> Option<Result<Date, Self::Error>> {
        Some(parse_order_date(record))
    }
    fn extract(
        &self,
        _existing: &[Directive],
        record: &csv::Record,
    ) -> Result<Vec<Directive>, Self::Error> {
        const ORDER_ID_COLUMN_INDEX: usize = 3;
        let isin = Commodity::try_from(&record[0]).map_err(|_| todo!())?;
        let security_name = &record[1];
        let date = parse_order_date(record)?;
        let order_id = &record[ORDER_ID_COLUMN_INDEX];
        let transaction_kind = TransactionKind::from_str(&record[4])?;
        let units = german_decimal::parse(&record[5]).map_err(|_| todo!())?;
        let amount = Amount::new(units, isin);
        let security_price = parse_amount(&record[7])?;
        let total = parse_amount(&record[9])?;
        let (amount, cost_basis, price, total) = match transaction_kind {
            TransactionKind::Buy => (amount, CostBasis::PerUnit(security_price), None, -total),
            TransactionKind::Sell => (-amount, CostBasis::Empty, Some(security_price), total),
        };
        let transaction = Transaction::on(date).tap_mut(|transaction| {
            let context = {
                let isin: &str = &isin;
                // TODO make this conversion in beancount_types
                let isin = <&Seg>::try_from(isin).expect("commodities are valid segments");
                TemplateContext { isin }
            };
            transaction
                .set_payee(&self.config.payee)
                .set_narration(format!("{transaction_kind:?} {security_name}"))
                .add_link(Link::try_from(format!("^bw-bank.{order_id}")).unwrap())
                .add_meta(common_keys::TRANSACTION_ID, order_id)
                .build_posting(self.config.account_template.render(&context), |posting| {
                    posting.set_amount(amount).set_cost(cost_basis);
                    posting.price = price;
                })
                .build_posting(self.config.reference_account.render(&context), |posting| {
                    posting.set_amount(total);
                });
            if let TransactionKind::Sell = transaction_kind {
                transaction
                    .build_posting(self.config.capital_gains_template.render(&context), |_| {});
            }
        });
        let price = Price::new(date, isin, security_price);
        Ok(vec![Directive::from(transaction), Directive::from(price)])
    }
}
impl ImporterBuilder {
    pub fn build(&self) -> Result<Importer, ImporterBuilderError> {
        let config =
            Config {
                account_template: self.account_template.clone().context(
                    UninitializedFieldSnafu {
                        field: "account_template",
                        importer: Importer::NAME,
                    },
                )?,
                capital_gains_template: self.capital_gains_template.clone().context(
                    UninitializedFieldSnafu {
                        field: "capital_gains_template",
                        importer: Importer::NAME,
                    },
                )?,
                payee: self.payee.clone().context(UninitializedFieldSnafu {
                    field: "payee",
                    importer: Importer::NAME,
                })?,
                reference_account: self.reference_account.clone().context(
                    UninitializedFieldSnafu {
                        field: "reference_account",
                        importer: Importer::NAME,
                    },
                )?,
            };
        Ok(Importer::new(config))
    }
}
#[derive(Clone, Copy, Debug)]
pub enum TemplateSelector {
    Isin,
}
impl FromStr for TemplateSelector {
    type Err = TemplateSelectorError;
    fn from_str(selector: &str) -> Result<Self, Self::Err> {
        match selector {
            "isin" => Ok(Self::Isin),
            _ => TemplateSelectorSnafu { selector }.fail(),
        }
    }
}
#[derive(Debug, Diagnostic, Snafu)]
#[snafu(display("unsupported context selector: {selector:?}"))]
pub struct TemplateSelectorError {
    selector: String,
    backtrace: Backtrace,
}
#[derive(Debug)]
struct TemplateContext<'c> {
    isin: &'c Seg,
}
impl Index<&TemplateSelector> for TemplateContext<'_> {
    type Output = Seg;
    fn index(&self, index: &TemplateSelector) -> &Self::Output {
        match index {
            TemplateSelector::Isin => self.isin,
        }
    }
}
#[derive(Clone, Copy, Debug)]
enum TransactionKind {
    Buy,
    Sell,
}
impl FromStr for TransactionKind {
    type Err = Error;
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "Kauf" => Ok(Self::Buy),
            "Verkauf" => Ok(Self::Sell),
            _ => todo!(),
        }
    }
}
fn parse_amount(cost: &str) -> Result<Amount, Error> {
    let (amount, commodity) = cost.split_once(' ').ok_or_else(|| todo!())?;
    let amount = german_decimal::parse(amount).map_err(|_| todo!())?;
    let commodity = Commodity::try_from(commodity).map_err(|_| todo!())?;
    Ok(Amount::new(amount, commodity))
}
fn parse_order_date(record: &csv::Record) -> Result<Date, Error> {
    use time::format_description::FormatItem;
    const DATE_COLUMN_INDEX: usize = 2;
    const DATE_FORMAT: &[FormatItem] = format_description!("[day].[month].[year]");
    Date::parse(&record[DATE_COLUMN_INDEX], DATE_FORMAT).map_err(|_| todo!())
}

pub mod portfolio;

[package]
name = "bw-bank"
authors.workspace      = true
edition.workspace      = true
publish.workspace      = true
rust-version.workspace = true
version.workspace      = true
[dependencies]
# Workspace dependencies
beancount-importers-framework.path = "../../framework"
beancount-types.path               = "../../common/beancount-types"
csv.path                           = "../csv"
german-decimal.path                = "../../common/german-decimal"
# Inherited dependencies
camino.workspace         = true
derive_builder.workspace = true
inventory.workspace      = true
itertools.workspace      = true
miette.workspace         = true
rust_decimal.workspace   = true
serde.workspace          = true
snafu.workspace          = true
tap.workspace            = true
time.workspace           = true

    "importers/bw-bank",

[[package]]
name = "bw-bank"
version = "0.0.0-dev.0"
dependencies = [
 "beancount-importers-framework",
 "beancount-types",
 "camino",
 "csv 0.0.0-dev.0",
 "derive_builder",
 "german-decimal",
 "inventory",
 "itertools",
 "miette",
 "rust_decimal",
 "serde",
 "snafu",
 "tap",
 "time 0.3.22",
]