use serde_json::Value;

use crate::{
    BucketKind, LoadedEntry, Result, UsageSummary,
    cli::{AgentReportKind, WeekDay},
    summarize_by_key, summarize_summaries_by_bucket, totals_json,
};

pub fn report_from_rows(rows: &[UsageSummary], kind: AgentReportKind) -> Value {
    let rows_json = rows
        .iter()
        .map(|row| ccusage_core::agent_summary_json(row, kind, false))
        .collect::<Vec<_>>();
    serde_json::json!({
        rows_key(kind): rows_json,
        "totals": totals_json(rows),
    })
}

pub(super) fn summary_period(row: &UsageSummary) -> &str {
    row.date
        .as_deref()
        .or(row.week.as_deref())
        .or(row.month.as_deref())
        .or(row.session_id.as_deref())
        .unwrap_or("")
}

pub fn summarize_entries(
    entries: &[LoadedEntry],
    kind: AgentReportKind,
) -> Result<Vec<UsageSummary>> {
    match kind {
        AgentReportKind::Daily => summarize_by_key(
            entries,
            |entry| entry.date.clone(),
            |date| (date.to_string(), None),
        ),
        AgentReportKind::Monthly => {
            let daily = summarize_entries(entries, AgentReportKind::Daily)?;
            Ok(summarize_summaries_by_bucket(
                &daily,
                BucketKind::Monthly,
                WeekDay::Sunday,
            ))
        }
        AgentReportKind::Session => summarize_by_key(
            entries,
            |entry| entry.session_id.to_string(),
            |session_id| (session_id.to_string(), None),
        )
        .map(|mut rows| {
            for row in &mut rows {
                row.session_id = row.date.take();
            }
            rows
        }),
        AgentReportKind::Weekly => {
            let daily = summarize_entries(entries, AgentReportKind::Daily)?;
            Ok(summarize_summaries_by_bucket(
                &daily,
                BucketKind::Weekly,
                WeekDay::Sunday,
            ))
        }
    }
}

fn rows_key(kind: AgentReportKind) -> &'static str {
    match kind {
        AgentReportKind::Daily => "daily",
        AgentReportKind::Weekly => "weekly",
        AgentReportKind::Monthly => "monthly",
        AgentReportKind::Session => "sessions",
    }
}