paddington 0.6.0

use chrono::{Datelike, TimeZone};
use clap::{Parser, Subcommand};
use serde::Deserialize;
use std::io::Read;
use std::process::Command;

mod config;
mod db;
mod setup;

use config::{BLUE, GRAY, GREEN, RED, RESET, YELLOW};

#[derive(Parser)]
#[command(name = "paddington", about = "Status line renderer for Claude Code")]
struct Cli {
    #[command(subcommand)]
    command: Option<Commands>,
}

#[derive(Subcommand)]
enum Commands {
    /// Show monthly cost analytics
    Stats {
        /// Month to display (YYYY-MM format, default: current)
        #[arg(long, conflicts_with = "all")]
        month: Option<String>,
        /// Compare against another month (YYYY-MM format)
        #[arg(long, conflicts_with = "all")]
        compare: Option<String>,
        /// Show all-time stats across all months
        #[arg(long)]
        all: bool,
    },
    /// Validate config and preview template with mock data
    Check,
    /// Browse session history
    History {
        /// Max sessions to show (default: 20)
        #[arg(long, short = 'n', default_value = "20")]
        limit: u32,
        /// Filter by project name
        #[arg(long, short)]
        project: Option<String>,
    },
    /// Configure Claude Code and Pi to use paddington
    Setup {
        /// Configure Claude Code only
        #[arg(long)]
        claude: bool,
        /// Configure Pi only
        #[arg(long)]
        pi: bool,
        /// Install into a specific Pi profile (e.g. "agent-prodsec")
        #[arg(long, requires = "pi")]
        profile: Option<String>,
        /// Overwrite existing configuration without prompting
        #[arg(long)]
        force: bool,
        /// Remove paddington configuration from agents
        #[arg(long)]
        uninstall: bool,
    },
}

#[derive(Deserialize, Default)]
pub struct Input {
    pub session_id: Option<String>,
    pub model: Option<Model>,
    pub cwd: Option<String>,
    pub workspace: Option<Workspace>,
    pub worktree: Option<Worktree>,
    pub pr: Option<PullRequest>,
    pub session_name: Option<String>,
    pub context_window: Option<ContextWindow>,
    pub cost: Option<Cost>,
    /// Pi-specific: provider name (e.g. "anthropic", "openai")
    pub provider: Option<String>,
    /// Pi-specific: reasoning/thinking level (e.g. "off", "high", "max")
    pub reasoning_level: Option<String>,
    /// Pi-specific: which coding agent is calling us
    pub agent: Option<String>,
    /// Pi-specific: cache token stats
    pub cache: Option<CacheStats>,
    /// Pi-specific: cumulative token counts (separate from context window)
    pub tokens: Option<TokenStats>,
    /// Pi-specific: git branch passed from the extension (avoids shelling out)
    #[serde(rename = "_git_branch")]
    pub git_branch_override: Option<String>,
    /// Pi-specific: aggregate subagent cost for this session
    pub subagent_cost_usd: Option<f64>,
    /// Pi-specific: individual subagent run details
    pub subagent_runs: Option<Vec<SubagentRun>>,
}

#[derive(Deserialize, Default)]
pub struct Model {
    pub id: Option<String>,
    pub display_name: Option<String>,
}

#[derive(Deserialize, Default)]
pub struct Workspace {
    pub project_dir: Option<String>,
    pub repo: Option<Repo>,
}

#[derive(Deserialize, Default)]
pub struct Repo {
    pub owner: Option<String>,
    pub name: Option<String>,
}

#[derive(Deserialize, Default)]
pub struct Worktree {
    pub name: Option<String>,
}

#[derive(Deserialize, Default)]
pub struct PullRequest {
    pub number: Option<serde_json::Value>,
    pub review_state: Option<String>,
}

#[derive(Deserialize, Default)]
pub struct ContextWindow {
    pub total_input_tokens: Option<u64>,
    pub total_output_tokens: Option<u64>,
    pub context_window_size: Option<u64>,
    pub used_percentage: Option<f64>,
}

#[derive(Deserialize, Default)]
pub struct Cost {
    pub total_cost_usd: Option<f64>,
    pub total_duration_ms: Option<u64>,
    pub total_lines_added: Option<u64>,
    pub total_lines_removed: Option<u64>,
}

#[derive(Deserialize, Default)]
pub struct CacheStats {
    pub read_tokens: Option<u64>,
    pub write_tokens: Option<u64>,
    pub hit_rate: Option<f64>,
}

#[derive(Deserialize, Default)]
pub struct TokenStats {
    pub input: Option<u64>,
    pub output: Option<u64>,
}

#[derive(Deserialize, Default)]
pub struct SubagentRun {
    pub run_id: Option<String>,
    pub agent: Option<String>,
    pub model: Option<String>,
    pub cost_usd: Option<f64>,
    pub input_tokens: Option<u64>,
    pub output_tokens: Option<u64>,
    pub duration_ms: Option<u64>,
}

fn git_branch(project_dir: &str) -> Option<String> {
    let try_symbolic = Command::new("git")
        .args(["--no-optional-locks", "symbolic-ref", "--short", "HEAD"])
        .current_dir(project_dir)
        .output()
        .ok()?;

    if try_symbolic.status.success() {
        return Some(
            String::from_utf8_lossy(&try_symbolic.stdout)
                .trim()
                .to_string(),
        );
    }

    let try_rev = Command::new("git")
        .args(["--no-optional-locks", "rev-parse", "--short", "HEAD"])
        .current_dir(project_dir)
        .output()
        .ok()?;

    if try_rev.status.success() {
        return Some(String::from_utf8_lossy(&try_rev.stdout).trim().to_string());
    }

    None
}

fn git_is_dirty(project_dir: &str) -> bool {
    Command::new("git")
        .args(["--no-optional-locks", "status", "--porcelain"])
        .current_dir(project_dir)
        .output()
        .ok()
        .map(|o| o.status.success() && !o.stdout.is_empty())
        .unwrap_or(false)
}

fn format_relative_time(delta: chrono::TimeDelta) -> String {
    let secs = delta.num_seconds();
    if secs < 60 {
        "just now".to_string()
    } else if secs < 3600 {
        format!("{}m ago", secs / 60)
    } else {
        format!("{}h ago", secs / 3600)
    }
}

pub fn format_duration(ms: u64) -> String {
    let total_secs = ms / 1000;
    let hrs = total_secs / 3600;
    let mins = (total_secs % 3600) / 60;
    let secs = total_secs % 60;

    if hrs > 0 {
        format!("{hrs}h {mins}m")
    } else if mins > 0 {
        format!("{mins}m {secs}s")
    } else {
        format!("{secs}s")
    }
}

fn main() {
    match Cli::try_parse() {
        Ok(cli) => match cli.command {
            None => render_status_line(),
            Some(Commands::Stats {
                month,
                compare,
                all,
            }) => {
                if all {
                    show_all_time_stats();
                } else {
                    show_stats(month, compare);
                }
            }
            Some(Commands::Check) => run_check(),
            Some(Commands::History { limit, project }) => show_history(limit, project),
            Some(Commands::Setup { claude, pi, profile, force, uninstall }) => {
                setup::run_setup(claude, pi, profile, force, uninstall);
            }
        },
        Err(e) if e.use_stderr() => {
            use clap::error::ErrorKind;
            match e.kind() {
                // Constraint errors mean clap recognized a subcommand but
                // the args are invalid — show the real error.
                ErrorKind::ArgumentConflict | ErrorKind::MissingRequiredArgument => {
                    e.exit()
                }
                // Everything else (e.g. UnknownArgument from piped JSON
                // passed as argv) — fall through to the stdin render path.
                _ => render_status_line(),
            }
        }
        Err(e) => e.exit(),
    }
}

fn render_status_line() {
    let mut raw = String::new();
    std::io::stdin().read_to_string(&mut raw).unwrap();

    let input: Input = serde_json::from_str(&raw).unwrap_or_default();

    let project_dir = input
        .workspace
        .as_ref()
        .and_then(|w| w.project_dir.as_deref())
        .unwrap_or("");

    // Compute monthly total (same DB logic as before)
    let monthly_total: Option<f64> = (|| -> Option<f64> {
        let session_id = input.session_id.as_deref()?;
        let cost_data = input.cost.as_ref()?;
        let conn = db::open_db().ok()?;
        let record = db::SessionRecord {
            session_id: session_id.to_string(),
            project_dir: input.workspace.as_ref().and_then(|w| w.project_dir.clone()),
            model_id: input.model.as_ref().and_then(|m| m.id.clone()),
            model_name: input.model.as_ref().and_then(|m| m.display_name.clone()),
            cost_usd: cost_data.total_cost_usd.unwrap_or(0.0),
            duration_ms: cost_data.total_duration_ms.unwrap_or(0),
            lines_added: cost_data.total_lines_added.unwrap_or(0),
            lines_removed: cost_data.total_lines_removed.unwrap_or(0),
            subagent_cost_usd: input.subagent_cost_usd.unwrap_or(0.0),
        };
        db::upsert_session(&conn, &record).ok()?;
        if let Some(ref runs) = input.subagent_runs {
            let run_records: Vec<db::SubagentRunRecord> = runs.iter().filter_map(|r| {
                Some(db::SubagentRunRecord {
                    session_id: session_id.to_string(),
                    run_id: r.run_id.clone()?,
                    agent_name: r.agent.clone(),
                    model_name: r.model.clone(),
                    cost_usd: r.cost_usd.unwrap_or(0.0),
                    input_tokens: r.input_tokens.unwrap_or(0),
                    output_tokens: r.output_tokens.unwrap_or(0),
                    duration_ms: r.duration_ms.unwrap_or(0),
                })
            }).collect();
            if !run_records.is_empty() {
                let _ = db::upsert_subagent_runs(&conn, &run_records);
            }
        }
        let now = chrono::Local::now();
        db::get_monthly_total(&conn, now.year(), now.month()).ok()
    })();

    // Compute git branch and dirty status
    // If the caller passed _git_branch (e.g. pi extension), use it and skip shelling out
    let has_git =
        !project_dir.is_empty() && std::path::Path::new(project_dir).join(".git").exists();
    let branch = if let Some(ref b) = input.git_branch_override {
        b.clone()
    } else if has_git {
        git_branch(project_dir).unwrap_or_default()
    } else {
        String::new()
    };
    let git_dirty = if input.git_branch_override.is_some() {
        false // pi extension doesn't provide dirty status, skip the shell call
    } else {
        has_git && git_is_dirty(project_dir)
    };

    // Load config
    let (cfg, config_err) = config::load_config();
    let template_str = cfg
        .format
        .as_ref()
        .and_then(|f| f.template.clone())
        .unwrap_or_else(|| config::DEFAULT_TEMPLATE.to_string());
    let budget_limit = config::resolve_budget_limit(&cfg);

    // Build context
    let ctx = config::build_context(&input, monthly_total, &branch, git_dirty, budget_limit, input.subagent_cost_usd);

    // Render
    let output = if let Some(err) = config_err {
        // Config error: show error on first line, render default for rest
        let error_line = config::render_error_line(&err);
        let default_output =
            config::render_template(config::DEFAULT_TEMPLATE, &ctx).unwrap_or_default();
        format!("{error_line}\n{default_output}")
    } else {
        match config::render_template(&template_str, &ctx) {
            Ok(rendered) => rendered,
            Err(err) => {
                let error_line = config::render_error_line(&err);
                let default_output =
                    config::render_template(config::DEFAULT_TEMPLATE, &ctx).unwrap_or_default();
                format!("{error_line}\n{default_output}")
            }
        }
    };

    print!("{output}");
}

fn run_check() {
    let path = config::config_path();
    let (cfg, config_err) = config::load_config();
    let template_str = cfg
        .format
        .as_ref()
        .and_then(|f| f.template.clone())
        .unwrap_or_else(|| config::DEFAULT_TEMPLATE.to_string());

    if std::path::Path::new(&path).exists() {
        println!("Config: {path}");
    } else {
        println!("Config: none found, using default template");
    }

    if let Some(err) = config_err {
        eprintln!("{RED}Error: {err}{RESET}");
        std::process::exit(1);
    }

    // Pre-compile template to check syntax before printing OK
    let env = minijinja::Environment::new();
    if let Err(err) = env.template_from_str(&template_str) {
        eprintln!("{RED}Template syntax error: {err}{RESET}");
        std::process::exit(1);
    }

    println!("{GREEN}Template syntax: OK{RESET}");

    // Test-render to catch template compilation errors
    let ctx = config::mock_context();
    match config::render_template(&template_str, &ctx) {
        Ok(rendered) => {
            println!("\n{GREEN}Preview:{RESET}\n");
            println!("{rendered}");
        }
        Err(err) => {
            eprintln!("{RED}Render error: {err}{RESET}");
            std::process::exit(1);
        }
    }
}

fn show_stats(month_arg: Option<String>, compare_arg: Option<String>) {
    let (year, month) = match month_arg.as_deref() {
        Some(s) => parse_month_arg(s),
        None => {
            let now = chrono::Local::now();
            (now.year(), now.month())
        }
    };

    let conn = match db::open_db_readonly() {
        Ok(c) => c,
        Err(e) => {
            eprintln!("Failed to open database: {e}");
            std::process::exit(1);
        }
    };

    let (total, subagent_cost, total_dur, total_added, total_removed) =
        match db::monthly_totals(&conn, year, month) {
            Ok(v) => v,
            Err(e) => {
                eprintln!("Database error: {e}");
                std::process::exit(1);
            }
        };
    let count = match db::monthly_session_count(&conn, year, month) {
        Ok(v) => v,
        Err(e) => {
            eprintln!("Database error: {e}");
            std::process::exit(1);
        }
    };

    // Budget summary
    let budget_limit = {
        let (cfg, _) = config::load_config();
        config::resolve_budget_limit(&cfg)
    };
    if let Some(limit) = budget_limit {
        let pct = (total / limit * 100.0).round();
        let remaining = (limit - total).max(0.0);
        let color = config::budget_color(pct);
        println!(
            "{color}Budget: ${total:.2} / ${limit:.2} ({pct:.0}% used, ${remaining:.2} remaining){RESET}"
        );
    }

    if count == 0 {
        println!("No session data recorded yet.");
        // Still run comparison if requested
        if let Some(ref cmp) = compare_arg {
            let (cy, cm) = parse_month_arg(cmp);
            show_comparison(&conn, year, month, cy, cm);
        }
        return;
    }

    let month_full = month_name_full(month);
    let month_short = month_name_short(month);
    let dur_str = format_duration(total_dur);
    let cost_str = if subagent_cost > 0.0 {
        let parent_cost = total - subagent_cost;
        format!("${total:.2} (${parent_cost:.2} + ${subagent_cost:.2} subagents)")
    } else {
        format!("${total:.2}")
    };
    println!(
        "{YELLOW}Monthly Cost: {cost_str}{RESET}  ({month_full} {year}, {count} session{}, {dur_str})",
        if count == 1 { "" } else { "s" }
    );
    if total_added > 0 || total_removed > 0 {
        println!(
            "  {GREEN}+{total_added}{RESET}{GRAY}/{RESET}{RED}-{total_removed}{RESET} {GRAY}lines{RESET}"
        );
    }
    println!();

    // By Day
    if let Ok(days) = db::daily_breakdown(&conn, year, month) {
        let max_cost = days.iter().map(|(_, c, _)| *c).fold(0.0_f64, f64::max);
        println!("{GREEN}By Day:{RESET}");
        for (day, cost, sessions) in &days {
            let bar = render_bar(*cost, max_cost, 10);
            println!(
                "  {month_short} {day:<2}   {YELLOW}${cost:.2}{RESET}  {bar}  {GRAY}({sessions} session{}){RESET}",
                if *sessions == 1 { "" } else { "s" }
            );
        }
        println!();
    }

    // By Model
    if let Ok(models) = db::model_breakdown(&conn, year, month) {
        println!("{GREEN}By Model:{RESET}");
        let name_width = models.iter().map(|(n, ..)| n.len()).max().unwrap_or(0);
        for (name, cost, dur) in &models {
            let pct = if total > 0.0 {
                cost / total * 100.0
            } else {
                0.0
            };
            let dur_str = format_duration(*dur);
            println!(
                "  {name:<name_width$}  {YELLOW}${cost:.2}{RESET}  {GRAY}({pct:.0}%) {dur_str}{RESET}"
            );
        }
        println!();
    }

    // By Project
    if let Ok(projects) = db::project_breakdown(&conn, year, month) {
        println!("{GREEN}By Project:{RESET}");
        let name_width = projects.iter().map(|(n, ..)| n.len()).max().unwrap_or(0);
        for (name, cost, dur, added, removed) in &projects {
            let pct = if total > 0.0 {
                cost / total * 100.0
            } else {
                0.0
            };
            let dur_str = format_duration(*dur);
            let lines = if *added > 0 || *removed > 0 {
                format!(" {GREEN}+{added}{RESET}{GRAY}/{RESET}{RED}-{removed}{RESET}")
            } else {
                String::new()
            };
            println!(
                "  {name:<name_width$}  {YELLOW}${cost:.2}{RESET}  {GRAY}({pct:.0}%) {dur_str}{RESET}{lines}"
            );
        }
        println!();
    }

    // By Subagent
    if let Ok(subagents) = db::subagent_breakdown(&conn, year, month)
        && !subagents.is_empty()
    {
        println!("{GREEN}By Subagent:{RESET}");
        let max_cost = subagents.iter().map(|(_, c, ..)| *c).fold(0.0_f64, f64::max);
        let name_width = subagents.iter().map(|(n, ..)| n.len()).max().unwrap_or(0);
        for (name, cost, runs, model, _tokens) in &subagents {
            let bar = render_bar(*cost, max_cost, 10);
            let run_label = if *runs == 1 { "run" } else { "runs" };
            println!(
                "  {name:<name_width$}  {YELLOW}${cost:.2}{RESET}  {bar}  {GRAY}({runs} {run_label}, {model}){RESET}"
            );
        }
        println!();
    }

    // Active Sessions (updated in the last 15 minutes)
    if let Ok(active) = db::active_sessions(&conn, 15)
        && !active.is_empty()
    {
        println!("{GREEN}Active Sessions:{RESET}");
        let now = chrono::Utc::now();
        let proj_width = active.iter().map(|s| s.project.len()).max().unwrap_or(0);
        for s in &active {
            let dur = format_duration(s.duration_ms);
            let ago = chrono::DateTime::parse_from_rfc3339(&s.updated_at)
                .ok()
                .map(|t| format_relative_time(now - t.to_utc()))
                .unwrap_or_default();
            println!(
                "  {:<proj_width$}  {YELLOW}${:.2}{RESET}  {GRAY}{dur} · {} · {ago}{RESET}",
                s.project, s.cost_usd, s.model
            );
        }
    }

    // All-time
    if let Ok((all_cost, all_count, all_dur)) = db::all_time_totals(&conn)
        && all_count > count
    {
        let dur_str = format_duration(all_dur);
        println!("\n{GRAY}All-time: ${all_cost:.2} across {all_count} sessions ({dur_str}){RESET}");
    }

    // Comparison (if requested)
    if let Some(ref cmp) = compare_arg {
        let (cy, cm) = parse_month_arg(cmp);
        show_comparison(&conn, year, month, cy, cm);
    }
}

fn show_all_time_stats() {
    let conn = match db::open_db_readonly() {
        Ok(c) => c,
        Err(e) => {
            eprintln!("Failed to open database: {e}");
            std::process::exit(1);
        }
    };

    let (total, subagent_cost, count, total_dur, total_added, total_removed) =
        match db::all_time_totals_full(&conn) {
            Ok(v) => v,
            Err(e) => {
                eprintln!("Database error: {e}");
                std::process::exit(1);
            }
        };

    if count == 0 {
        println!("No session data recorded yet.");
        return;
    }

    let dur_str = format_duration(total_dur);
    let cost_str = if subagent_cost > 0.0 {
        let parent_cost = total - subagent_cost;
        format!("${total:.2} (${parent_cost:.2} + ${subagent_cost:.2} subagents)")
    } else {
        format!("${total:.2}")
    };
    println!(
        "{YELLOW}All-Time Cost: {cost_str}{RESET}  ({count} session{}, {dur_str})",
        if count == 1 { "" } else { "s" }
    );
    if total_added > 0 || total_removed > 0 {
        println!(
            "  {GREEN}+{total_added}{RESET}{GRAY}/{RESET}{RED}-{total_removed}{RESET} {GRAY}lines{RESET}"
        );
    }
    println!();

    // By Month
    if let Ok(months) = db::monthly_breakdown(&conn) {
        let max_cost = months.iter().map(|(.., c, _, _)| *c).fold(0.0_f64, f64::max);
        println!("{GREEN}By Month:{RESET}");
        for (year, month, cost, sessions, dur) in &months {
            let bar = render_bar(*cost, max_cost, 10);
            let mon = month_name_short(*month);
            let dur_str = format_duration(*dur);
            let pct = if total > 0.0 {
                cost / total * 100.0
            } else {
                0.0
            };
            println!(
                "  {mon} {year}  {YELLOW}${cost:.2}{RESET}  {bar}  {GRAY}({sessions} session{}, {dur_str}, {pct:.0}%){RESET}",
                if *sessions == 1 { "" } else { "s" }
            );
        }
        println!();
    }

    // By Model
    if let Ok(models) = db::all_time_model_breakdown(&conn) {
        println!("{GREEN}By Model:{RESET}");
        let name_width = models.iter().map(|(n, ..)| n.len()).max().unwrap_or(0);
        for (name, cost, dur) in &models {
            let pct = if total > 0.0 {
                cost / total * 100.0
            } else {
                0.0
            };
            let dur_str = format_duration(*dur);
            println!(
                "  {name:<name_width$}  {YELLOW}${cost:.2}{RESET}  {GRAY}({pct:.0}%) {dur_str}{RESET}"
            );
        }
        println!();
    }

    // By Project
    if let Ok(projects) = db::all_time_project_breakdown(&conn) {
        println!("{GREEN}By Project:{RESET}");
        let name_width = projects.iter().map(|(n, ..)| n.len()).max().unwrap_or(0);
        for (name, cost, dur, added, removed) in &projects {
            let pct = if total > 0.0 {
                cost / total * 100.0
            } else {
                0.0
            };
            let dur_str = format_duration(*dur);
            let lines = if *added > 0 || *removed > 0 {
                format!(" {GREEN}+{added}{RESET}{GRAY}/{RESET}{RED}-{removed}{RESET}")
            } else {
                String::new()
            };
            println!(
                "  {name:<name_width$}  {YELLOW}${cost:.2}{RESET}  {GRAY}({pct:.0}%) {dur_str}{RESET}{lines}"
            );
        }
        println!();
    }

    // By Subagent
    if let Ok(subagents) = db::all_time_subagent_breakdown(&conn)
        && !subagents.is_empty()
    {
        println!("{GREEN}By Subagent:{RESET}");
        let max_cost = subagents.iter().map(|(_, c, ..)| *c).fold(0.0_f64, f64::max);
        let name_width = subagents.iter().map(|(n, ..)| n.len()).max().unwrap_or(0);
        for (name, cost, runs, model, _tokens) in &subagents {
            let bar = render_bar(*cost, max_cost, 10);
            let run_label = if *runs == 1 { "run" } else { "runs" };
            println!(
                "  {name:<name_width$}  {YELLOW}${cost:.2}{RESET}  {bar}  {GRAY}({runs} {run_label}, {model}){RESET}"
            );
        }
        println!();
    }

    // Active Sessions
    if let Ok(active) = db::active_sessions(&conn, 15)
        && !active.is_empty()
    {
        println!("{GREEN}Active Sessions:{RESET}");
        let now = chrono::Utc::now();
        let proj_width = active.iter().map(|s| s.project.len()).max().unwrap_or(0);
        for s in &active {
            let dur = format_duration(s.duration_ms);
            let ago = chrono::DateTime::parse_from_rfc3339(&s.updated_at)
                .ok()
                .map(|t| format_relative_time(now - t.to_utc()))
                .unwrap_or_default();
            println!(
                "  {:<proj_width$}  {YELLOW}${:.2}{RESET}  {GRAY}{dur} · {} · {ago}{RESET}",
                s.project, s.cost_usd, s.model
            );
        }
    }
}

fn show_comparison(
    conn: &rusqlite::Connection,
    sel_year: i32,
    sel_month: u32,
    cmp_year: i32,
    cmp_month: u32,
) {
    let (cmp_cost, _, cmp_dur, _, _) = match db::monthly_totals(conn, cmp_year, cmp_month) {
        Ok(v) => v,
        Err(e) => {
            eprintln!("Database error: {e}");
            return;
        }
    };
    let cmp_count = match db::monthly_session_count(conn, cmp_year, cmp_month) {
        Ok(v) => v,
        Err(e) => {
            eprintln!("Database error: {e}");
            return;
        }
    };

    let cmp_month_name = month_name_full(cmp_month);

    if cmp_count == 0 {
        println!("\nNo data for {cmp_month_name} {cmp_year}.");
        return;
    }

    let (sel_cost, _, sel_dur, _, _) =
        db::monthly_totals(conn, sel_year, sel_month).unwrap_or((0.0, 0.0, 0, 0, 0));
    let sel_count = db::monthly_session_count(conn, sel_year, sel_month).unwrap_or_default();

    // Cost delta
    let cost_delta = sel_cost - cmp_cost;
    let cost_sign = if cost_delta >= 0.0 { "+" } else { "-" };
    let cost_pct_str = if cmp_cost > 0.0 {
        let pct = (cost_delta.abs() / cmp_cost * 100.0).round() as i64;
        format!(", {cost_sign}{pct}%")
    } else {
        String::new()
    };

    // Session delta
    let session_delta = sel_count as i64 - cmp_count as i64;
    let session_sign = if session_delta >= 0 { "+" } else { "" };

    // Duration delta
    let cmp_dur_str = format_duration(cmp_dur);
    let sel_dur_str = format_duration(sel_dur);
    let dur_pct_str = if cmp_dur > 0 {
        let pct = ((sel_dur as f64 - cmp_dur as f64) / cmp_dur as f64 * 100.0).round() as i64;
        let dur_sign = if pct >= 0 { "+" } else { "" };
        format!("  ({dur_sign}{pct}%)")
    } else {
        String::new()
    };

    println!("\n{GREEN}vs {cmp_month_name} {cmp_year}:{RESET}");
    println!(
        "  Cost:     {YELLOW}${cmp_cost:.2}{RESET} -> {YELLOW}${sel_cost:.2}{RESET}  ({cost_sign}${}{cost_pct_str})",
        cost_delta.abs()
    );
    println!("  Sessions: {cmp_count} -> {sel_count}  ({session_sign}{session_delta})");
    println!("  Duration: {GRAY}{cmp_dur_str}{RESET} -> {GRAY}{sel_dur_str}{RESET}{dur_pct_str}");
}

fn show_history(limit: u32, project_filter: Option<String>) {
    let conn = match db::open_db_readonly() {
        Ok(c) => c,
        Err(e) => {
            eprintln!("Failed to open database: {e}");
            std::process::exit(1);
        }
    };

    let sessions = match db::list_sessions(&conn, limit, project_filter.as_deref()) {
        Ok(v) => v,
        Err(e) => {
            eprintln!("Database error: {e}");
            std::process::exit(1);
        }
    };

    if sessions.is_empty() {
        println!("No sessions found.");
        return;
    }

    let proj_width = sessions.iter().map(|s| s.project.len()).max().unwrap_or(0);
    let model_width = sessions.iter().map(|s| s.model.len()).max().unwrap_or(0);

    for s in &sessions {
        let date = chrono::DateTime::parse_from_rfc3339(&s.started_at)
            .map(|dt| {
                chrono::Local
                    .from_utc_datetime(&dt.naive_utc())
                    .format("%Y-%m-%d")
                    .to_string()
            })
            .unwrap_or_else(|_| s.started_at[..10].to_string());
        let dur = format_duration(s.duration_ms);
        let lines = if s.lines_added > 0 || s.lines_removed > 0 {
            format!(
                " {GREEN}+{}{RESET}{GRAY}/{RESET}{RED}-{}{RESET}",
                s.lines_added, s.lines_removed
            )
        } else {
            String::new()
        };
        println!(
            "  {GRAY}{date}{RESET}  {BLUE}{:<proj_width$}{RESET}  {:<model_width$}  {YELLOW}${:.2}{RESET}  {GRAY}{dur}{RESET}{lines}",
            s.project, s.model, s.cost_usd
        );
    }
}

fn parse_month_arg(s: &str) -> (i32, u32) {
    let parts: Vec<&str> = s.split('-').collect();
    if parts.len() == 2
        && let (Ok(y), Ok(m)) = (parts[0].parse::<i32>(), parts[1].parse::<u32>())
        && (1..=12).contains(&m)
    {
        return (y, m);
    }
    eprintln!("Invalid month format '{s}', expected YYYY-MM");
    std::process::exit(1);
}

fn month_name_short(month: u32) -> &'static str {
    match month {
        1 => "Jan",
        2 => "Feb",
        3 => "Mar",
        4 => "Apr",
        5 => "May",
        6 => "Jun",
        7 => "Jul",
        8 => "Aug",
        9 => "Sep",
        10 => "Oct",
        11 => "Nov",
        12 => "Dec",
        _ => "???",
    }
}

fn month_name_full(month: u32) -> &'static str {
    match month {
        1 => "January",
        2 => "February",
        3 => "March",
        4 => "April",
        5 => "May",
        6 => "June",
        7 => "July",
        8 => "August",
        9 => "September",
        10 => "October",
        11 => "November",
        12 => "December",
        _ => "???",
    }
}

fn render_bar(value: f64, max: f64, width: usize) -> String {
    let filled = if max > 0.0 {
        (value / max * width as f64).round() as usize
    } else {
        0
    };
    let empty = width.saturating_sub(filled);
    format!(
        "{GREEN}{}{GRAY}{}{RESET}",
        "█".repeat(filled),
        "░".repeat(empty)
    )
}

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

    #[test]
    fn test_format_duration() {
        assert_eq!(format_duration(0), "0s");
        assert_eq!(format_duration(5_000), "5s");
        assert_eq!(format_duration(65_000), "1m 5s");
        assert_eq!(format_duration(3_661_000), "1h 1m");
    }

    #[test]
    fn test_show_comparison_no_data_message() {
        // show_comparison with empty DB should print "No data for..."
        // We can't easily capture stdout in unit tests, but we can verify
        // the DB queries return zero for a month with no data
        let conn = db::open_db_in_memory().unwrap();
        let count = db::monthly_session_count(&conn, 2026, 1).unwrap();
        assert_eq!(count, 0);
    }

    #[test]
    fn test_comparison_delta_math() {
        // Cost delta: 85.50 - 142.00 = -56.50
        let cmp_cost = 142.0_f64;
        let sel_cost = 85.5_f64;
        let delta = sel_cost - cmp_cost;
        assert!((delta - (-56.5)).abs() < f64::EPSILON);
        let pct = (delta / cmp_cost * 100.0).round() as i64;
        assert_eq!(pct, -40);
    }

    #[test]
    fn test_comparison_zero_cost_no_percentage() {
        let cmp_cost = 0.0_f64;
        // When cmp_cost is 0, percentage should be omitted
        assert!(!(cmp_cost > 0.0));
    }
}