budget_tracker_tui 1.4.0

//! CSV serialization: transaction import/export (used by the one-time migration and the
//! Import/Export actions) and parsing of the embedded category seed used to initialize the
//! database. The database itself is the persistence layer; this module only handles CSV.
use crate::model::{CategoryInfo, Transaction, TransactionType};
use std::fs::{File, create_dir_all};
use std::io::{Error, ErrorKind};
use std::path::Path;
use std::result::Result as StdResult;

pub(crate) fn load_transactions(data_path: &Path) -> StdResult<Vec<Transaction>, Error> {
    if !data_path.exists() {
        if let Some(parent) = data_path.parent() {
            create_dir_all(parent)?;
        }
        return Ok(vec![]);
    }

    let file = File::open(data_path)?;
    let mut rdr = csv::ReaderBuilder::new().flexible(true).from_reader(file);
    let mut transactions = Vec::new();
    let headers = rdr
        .headers()
        .map_err(|e| {
            Error::new(
                ErrorKind::InvalidData,
                format!("Failed to read headers from {}: {}", data_path.display(), e),
            )
        })?
        .clone();

    for (index, result) in rdr.deserialize().enumerate() {
        let transaction: Transaction = result.map_err(|e| {
            Error::new(
                ErrorKind::InvalidData,
                format!(
                    "Failed to parse transaction at row {} in {}: {}. Headers: {:?}",
                    index + 2,
                    data_path.display(),
                    e,
                    headers
                ),
            )
        })?;
        transactions.push(transaction);
    }
    Ok(transactions)
}

pub(crate) fn save_transactions(
    transactions: &[Transaction],
    data_path: &Path,
) -> StdResult<(), Error> {
    if let Some(parent) = data_path.parent() {
        create_dir_all(parent)?;
    }

    let file = File::create(data_path)?;
    let mut wtr = csv::Writer::from_writer(file);
    for transaction in transactions {
        wtr.serialize(transaction).map_err(|e| {
            Error::other(format!(
                "Failed to serialize transaction {:?} to {}: {}",
                transaction,
                data_path.display(),
                e
            ))
        })?;
    }
    wtr.flush()?;
    Ok(())
}

/// Parse the embedded category list used to seed the database on first run.
pub(crate) fn load_seed_categories() -> StdResult<Vec<CategoryInfo>, Error> {
    let embedded_csv_data = include_str!("../budget_categories.csv");

    let mut rdr = csv::Reader::from_reader(embedded_csv_data.as_bytes());
    let mut categories = Vec::new();
    let mut header_error = None;

    let headers = rdr.headers()?.clone();
    let type_idx = headers
        .iter()
        .position(|h| h.eq_ignore_ascii_case("Type"))
        .ok_or_else(|| {
            Error::new(
                ErrorKind::InvalidData,
                "Embedded category data missing required header: Type",
            )
        })?;
    let cat_idx = headers
        .iter()
        .position(|h| h.eq_ignore_ascii_case("Category"))
        .ok_or_else(|| {
            Error::new(
                ErrorKind::InvalidData,
                "Embedded category data missing required header: Category",
            )
        })?;
    let subcat_idx = headers
        .iter()
        .position(|h| h.eq_ignore_ascii_case("Subcategory"))
        .ok_or_else(|| {
            Error::new(
                ErrorKind::InvalidData,
                "Embedded category data missing required header: Subcategory",
            )
        })?;

    for (index, result) in rdr.records().enumerate() {
        let record = result.map_err(|e| {
            Error::new(
                ErrorKind::InvalidData,
                format!(
                    "Failed to read record at row {} from embedded category data: {}",
                    index + 1,
                    e
                ),
            )
        })?;

        let type_str = record
            .get(type_idx)
            .ok_or_else(|| {
                Error::new(
                    ErrorKind::InvalidData,
                    format!("Missing Type at row {} in embedded data", index + 1),
                )
            })?
            .trim();
        let cat_str = record
            .get(cat_idx)
            .ok_or_else(|| {
                Error::new(
                    ErrorKind::InvalidData,
                    format!("Missing Category at row {} in embedded data", index + 1),
                )
            })?
            .trim();
        let subcat_str = record
            .get(subcat_idx)
            .ok_or_else(|| {
                Error::new(
                    ErrorKind::InvalidData,
                    format!("Missing Subcategory at row {} in embedded data", index + 1),
                )
            })?
            .trim();

        let transaction_type = match type_str {
            t if t.eq_ignore_ascii_case("Income") => TransactionType::Income,
            t if t.eq_ignore_ascii_case("Expense") => TransactionType::Expense,
            _ => {
                if header_error.is_none() {
                    header_error = Some(Error::new(
                        ErrorKind::InvalidData,
                        format!(
                            "Invalid Type '{}' at row {} in embedded data",
                            type_str,
                            index + 1
                        ),
                    ));
                }
                continue;
            }
        };

        if cat_str.is_empty() {
            continue;
        }

        categories.push(CategoryInfo {
            transaction_type,
            category: cat_str.to_string(),
            subcategory: subcat_str.to_string(),
        });
    }

    if let Some(err) = header_error {
        Err(err)
    } else {
        Ok(categories)
    }
}