use byte_unit::{Byte, UnitType};

use clap::{CommandFactory, Parser, ValueEnum};
use clap_complete::{generate, Shell};
use colored::*;
use comfy_table::presets::UTF8_FULL;
use comfy_table::{Attribute, Cell, CellAlignment, Color, ContentArrangement, Table};
use csv::WriterBuilder;
use std::cmp::Ordering;
use std::io::Write;
use std::path::{Path, PathBuf};
use std::str::FromStr;

pub mod scan;
pub use scan::{
    scan_tree, EntryType, FileIdentity, Node, ScanControl, ScanError, ScanIssue, ScanOptions,
    ScanReport,
};

#[derive(Parser, Debug, Clone)]
#[command(author, version, about, long_about = None)]
#[command(disable_version_flag = true)]
pub struct Args {
    /// Print version
    #[arg(short = 'v', long, action = clap::ArgAction::Version)]
    pub version: Option<bool>,

    /// Directory to analyze
    #[arg(default_value = ".")]
    pub path: PathBuf,

    /// Minimum size filter (e.g. "10MB", "1gb")
    #[arg(short = 'm', long)]
    pub min_size: Option<String>,

    /// Limit the number of results per table
    #[arg(short = 'n', long)]
    pub number: Option<usize>,

    /// Sort by columns (e.g. "type:asc,size:dsc").
    /// defaults to size:dsc.
    /// Columns: name, type, size (disk usage), apparent (logical), blocks.
    #[arg(long)]
    pub sort: Option<String>,

    /// Show apparent size (logical file length) in addition to disk usage
    #[arg(short = 'a', long)]
    pub apparent: bool,

    /// Depth to traverse (0 = only immediate children)
    #[arg(short, long, default_value = "0")]
    pub depth: usize,

    /// Display full absolute paths
    #[arg(short = 'f', long, conflicts_with = "path_relative")]
    pub path_full: bool,

    /// Display paths relative to current directory (default)
    #[arg(long)]
    pub path_relative: bool,

    /// Number of threads to use (defaults to available logical CPUs)
    #[arg(short = 'j', long = "threads")]
    pub threads: Option<usize>,

    /// Stay on the target's filesystem instead of descending into other mounts
    #[arg(short = 'x', long)]
    pub one_file_system: bool,

    /// Generate shell completions
    #[arg(long, value_enum)]
    pub completions: Option<Shell>,

    /// Respect .gitignore and .ignore files
    #[arg(short = 'i', long)]
    pub ignore: bool,

    /// Output format
    #[arg(long, value_enum, default_value_t = OutputFormat::Text)]
    pub format: OutputFormat,

    /// Save output to file (optional filename, defaults to timestamped name)
    #[arg(long, num_args(0..=1), default_missing_value = "_AUTO_")]
    pub save: Option<PathBuf>,

    /// Precision for size output (decimal places)
    #[arg(long, default_value = "2")]
    pub precision: usize,

    /// Unit system to use
    #[arg(long, value_enum, default_value_t = UnitSystem::Binary)]
    pub units: UnitSystem,

    /// Show comparison between total and non-ignored files
    #[arg(short = 'c', long)]
    pub compare: bool,

    /// Generate man page to the specified output directory
    #[arg(long, hide = true)]
    pub generate_man_page: Option<std::path::PathBuf>,
}

#[derive(ValueEnum, Clone, Debug, PartialEq, Eq)]
pub enum OutputFormat {
    Text,
    Csv,
    Json,
}

#[derive(ValueEnum, Clone, Debug, PartialEq, Eq)]
pub enum UnitSystem {
    Binary,
    Decimal,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub enum SortColumn {
    Name,
    Type,
    Disk,
    Apparent,
    Blocks,
}

impl FromStr for SortColumn {
    type Err = String;
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s.to_lowercase().as_str() {
            "name" | "n" => Ok(SortColumn::Name),
            "type" | "t" => Ok(SortColumn::Type),
            "size" | "s" | "disk" | "d" => Ok(SortColumn::Disk),
            "apparent" | "a" => Ok(SortColumn::Apparent),
            "blocks" | "b" => Ok(SortColumn::Blocks),
            _ => Err(format!("Unknown column: {s}")),
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub enum SortDirection {
    Asc,
    Dsc,
}

impl FromStr for SortDirection {
    type Err = String;
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s.to_lowercase().as_str() {
            "asc" | "a" => Ok(SortDirection::Asc),
            "dsc" | "d" | "desc" => Ok(SortDirection::Dsc),
            _ => Err(format!("Unknown direction: {s}")),
        }
    }
}

/// Returns whether the scan completed without missing entries. The caller
/// chooses the exit status; partial reports remain available to the user.
pub fn run(args: Args, mut writer: &mut dyn Write) -> bool {
    if let Some(shell) = args.completions {
        let mut cmd = Args::command();
        let name = cmd.get_name().to_string();
        generate(shell, &mut cmd, name, &mut std::io::stdout());
        return true;
    }

    if let Some(out_dir) = args.generate_man_page {
        let cmd = Args::command();
        let man = clap_mangen::Man::new(cmd);
        let mut buffer: Vec<u8> = Default::default();
        man.render(&mut buffer).expect("Failed to render man page");

        std::fs::create_dir_all(&out_dir).expect("Failed to create man page directory");
        let file_path = out_dir.join("sized.1");
        std::fs::write(&file_path, buffer).expect("Failed to write man page");
        println!("Man page generated at {}", file_path.display());
        return true;
    }

    let target_path = args.path.clone();

    let min_bytes = if let Some(size_str) = &args.min_size {
        match Byte::parse_str(size_str, true) {
            Ok(byte) => byte.as_u64(),
            Err(e) => {
                eprintln!("Error parsing size '{size_str}': {e}");
                std::process::exit(1);
            }
        }
    } else {
        0
    };

    let sort_criteria = parse_sort_arg(args.sort.as_deref().unwrap_or("size:dsc"));

    if args.format == OutputFormat::Csv {
        if args.apparent {
            writeln!(writer, "Path,Type,Apparent(Bytes),DiskUsage(Bytes),Blocks")
                .expect("Failed to write CSV header");
        } else {
            writeln!(writer, "Path,Type,DiskUsage(Bytes),Blocks")
                .expect("Failed to write CSV header");
        }
    }

    let report = match scan_tree(
        &target_path,
        &ScanOptions {
            respect_ignore: args.ignore,
            compare_ignore: args.compare,
            stay_on_filesystem: args.one_file_system,
            threads: args.threads,
        },
        &ScanControl::default(),
    ) {
        Ok(report) => report,
        Err(e) => {
            eprintln!("Error: {e}");
            return false;
        }
    };
    for issue in &report.issues {
        eprintln!(
            "Warning: incomplete scan at '{}': {}",
            issue.path.display(),
            issue.message
        );
    }
    let root_node = report.root;

    if root_node.size_bytes < min_bytes {
        if args.format == OutputFormat::Text {
            writeln!(writer, "Root directory is smaller than minimum size.").ok();
        }
        return root_node.complete;
    }

    process_node_recursive(&mut writer, &root_node, 0, &args, min_bytes, &sort_criteria);
    root_node.complete
}

pub fn build_tree(path: &Path, ignore: bool, compare: bool) -> Node {
    // Compatibility helper; callers needing diagnostics should use scan_tree.
    scan_tree(
        path,
        &ScanOptions {
            respect_ignore: ignore,
            compare_ignore: compare,
            ..ScanOptions::default()
        },
        &ScanControl::default(),
    )
    .map(|report| report.root)
    .unwrap_or_else(|_| Node::unavailable(path))
}

fn process_node_recursive(
    writer: &mut dyn Write,
    node: &Node,
    current_depth: usize,
    args: &Args,
    min_bytes: u64,
    sort_criteria: &[(SortColumn, SortDirection)],
) {
    let mut display_children: Vec<&Node> = node
        .children
        .iter()
        .filter(|c| c.size_bytes >= min_bytes)
        .collect();

    display_children.sort_by(|a, b| compare_nodes(a, b, sort_criteria));

    if let Some(n) = args.number {
        if n < display_children.len() {
            display_children.truncate(n);
        }
    }

    let show_relative = !args.path_full;
    let relative_path = if show_relative {
        let cwd = std::env::current_dir().unwrap_or_default();
        node.path
            .strip_prefix(&cwd)
            .unwrap_or(&node.path)
            .display()
            .to_string()
    } else {
        node.path
            .canonicalize()
            .unwrap_or(node.path.clone())
            .display()
            .to_string()
    };

    print_output(
        writer,
        node,
        &display_children,
        args,
        &relative_path,
        current_depth,
    );

    if current_depth < args.depth {
        for child in display_children {
            if child.entry_type == EntryType::Dir {
                process_node_recursive(
                    writer,
                    child,
                    current_depth + 1,
                    args,
                    min_bytes,
                    sort_criteria,
                );
            }
        }
    }
}

pub fn compare_nodes(a: &Node, b: &Node, criteria: &[(SortColumn, SortDirection)]) -> Ordering {
    for (col, dir) in criteria {
        let order = match col {
            SortColumn::Name => a.path.file_name().cmp(&b.path.file_name()),
            SortColumn::Type => a.entry_type.cmp(&b.entry_type),
            SortColumn::Disk => a.blocks.cmp(&b.blocks),
            SortColumn::Apparent => a.size_bytes.cmp(&b.size_bytes),
            SortColumn::Blocks => a.blocks.cmp(&b.blocks),
        };

        if order != Ordering::Equal {
            return match dir {
                SortDirection::Asc => order,
                SortDirection::Dsc => order.reverse(),
            };
        }
    }
    Ordering::Equal
}

pub fn parse_sort_arg(s: &str) -> Vec<(SortColumn, SortDirection)> {
    s.split(',')
        .filter_map(|part| {
            let parts: Vec<&str> = part.split(':').collect();
            if parts.is_empty() {
                return None;
            }

            let col_str = parts[0];
            let col = SortColumn::from_str(col_str).ok()?;

            let dir = if parts.len() > 1 {
                SortDirection::from_str(parts[1]).unwrap_or(SortDirection::Dsc)
            } else {
                match col {
                    SortColumn::Name | SortColumn::Type => SortDirection::Asc,
                    _ => SortDirection::Dsc,
                }
            };
            Some((col, dir))
        })
        .collect()
}

fn print_output(
    writer: &mut dyn Write,
    parent_node: &Node,
    children: &[&Node],
    args: &Args,
    relative_path: &str,
    depth: usize,
) {
    match args.format {
        OutputFormat::Text => print_text(writer, parent_node, children, args, relative_path, depth),
        OutputFormat::Csv => print_csv(writer, children, args),
        OutputFormat::Json => print_json(writer, parent_node, children, args),
    }
}

fn print_text(
    writer: &mut dyn Write,
    parent_node: &Node,
    children: &[&Node],
    args: &Args,
    relative_path: &str,
    depth: usize,
) {
    if depth > 0 {
        writeln!(writer, "{}", "-".repeat(60).dimmed()).ok();
    }
    writeln!(writer, "\n{}", relative_path.bold().blue()).ok();

    let unit_type = match args.units {
        UnitSystem::Binary => UnitType::Binary,
        UnitSystem::Decimal => UnitType::Decimal,
    };

    if parent_node.accessible {
        let total_usage = Byte::from_u64(parent_node.blocks * 512).get_appropriate_unit(unit_type);

        let mut summary = if args.apparent {
            let total_apparent =
                Byte::from_u64(parent_node.size_bytes).get_appropriate_unit(unit_type);
            format!(
                "Total Apparent: {} / Disk Usage: {} ({} blocks)",
                format!(
                    "{:.precision$} {}",
                    total_apparent.get_value(),
                    total_apparent.get_unit(),
                    precision = args.precision
                )
                .bold()
                .green(),
                format!(
                    "{:.precision$} {}",
                    total_usage.get_value(),
                    total_usage.get_unit(),
                    precision = args.precision
                )
                .bold()
                .green(),
                parent_node.blocks
            )
        } else {
            format!(
                "Disk Usage: {} ({} blocks)",
                format!(
                    "{:.precision$} {}",
                    total_usage.get_value(),
                    total_usage.get_unit(),
                    precision = args.precision
                )
                .bold()
                .green(),
                parent_node.blocks
            )
        };

        if args.compare {
            let total_usage_filtered =
                Byte::from_u64(parent_node.blocks_filtered * 512).get_appropriate_unit(unit_type);

            if args.apparent {
                let total_apparent_filtered =
                    Byte::from_u64(parent_node.size_bytes_filtered).get_appropriate_unit(unit_type);

                summary.push_str(&format!(
                    "\nFiltered Apparent: {} / Filtered Disk Usage: {} ({} blocks)",
                    format!(
                        "{:.precision$} {}",
                        total_apparent_filtered.get_value(),
                        total_apparent_filtered.get_unit(),
                        precision = args.precision
                    )
                    .bold()
                    .cyan(),
                    format!(
                        "{:.precision$} {}",
                        total_usage_filtered.get_value(),
                        total_usage_filtered.get_unit(),
                        precision = args.precision
                    )
                    .bold()
                    .cyan(),
                    parent_node.blocks_filtered
                ));
            } else {
                summary.push_str(&format!(
                    "\nFiltered Disk Usage: {} ({} blocks)",
                    format!(
                        "{:.precision$} {}",
                        total_usage_filtered.get_value(),
                        total_usage_filtered.get_unit(),
                        precision = args.precision
                    )
                    .bold()
                    .cyan(),
                    parent_node.blocks_filtered
                ));
            }
        }

        writeln!(writer, "{summary}").ok();
    } else {
        writeln!(writer, "Total size: {}", "Access Denied".bold().red()).ok();
    }

    if children.is_empty() {
        if parent_node.accessible {
            writeln!(writer, "(No children)").ok();
        }
        return;
    }

    let mut table = Table::new();
    table
        .load_preset(UTF8_FULL)
        .set_content_arrangement(ContentArrangement::Dynamic);

    let mut headers = vec![
        Cell::new("Name").add_attribute(Attribute::Bold),
        Cell::new("Type").add_attribute(Attribute::Bold),
    ];

    if args.apparent {
        headers.push(
            Cell::new("Apparent")
                .add_attribute(Attribute::Bold)
                .set_alignment(CellAlignment::Right),
        );
    }

    headers.push(
        Cell::new("Disk Usage")
            .add_attribute(Attribute::Bold)
            .set_alignment(CellAlignment::Right),
    );

    if args.compare {
        if args.apparent {
            headers.push(
                Cell::new("App. Filtered")
                    .add_attribute(Attribute::Bold)
                    .set_alignment(CellAlignment::Right),
            );
        }
        headers.push(
            Cell::new("Disk Filtered")
                .add_attribute(Attribute::Bold)
                .set_alignment(CellAlignment::Right),
        );
    }

    headers.push(
        Cell::new("Blocks")
            .add_attribute(Attribute::Bold)
            .set_alignment(CellAlignment::Right),
    );

    table.set_header(headers);

    for child in children {
        let name = child.path.file_name().unwrap_or_default().to_string_lossy();
        let color = if child.entry_type == EntryType::Dir {
            Color::Blue
        } else {
            Color::Cyan
        };

        if child.accessible {
            let mut row = vec![
                Cell::new(name).fg(color),
                Cell::new(&child.entry_type).fg(Color::Yellow),
            ];

            if args.apparent {
                let child_byte = Byte::from_u64(child.size_bytes).get_appropriate_unit(unit_type);
                row.push(
                    Cell::new(format!(
                        "{:.precision$} {}",
                        child_byte.get_value(),
                        child_byte.get_unit(),
                        precision = args.precision
                    ))
                    .fg(Color::Green)
                    .set_alignment(CellAlignment::Right),
                );
            }

            let disk_usage_byte =
                Byte::from_u64(child.blocks * 512).get_appropriate_unit(unit_type);
            row.push(
                Cell::new(format!(
                    "{:.precision$} {}",
                    disk_usage_byte.get_value(),
                    disk_usage_byte.get_unit(),
                    precision = args.precision
                ))
                .fg(Color::Green)
                .set_alignment(CellAlignment::Right),
            );

            if args.compare {
                if args.apparent {
                    let child_byte_filtered =
                        Byte::from_u64(child.size_bytes_filtered).get_appropriate_unit(unit_type);
                    row.push(
                        Cell::new(format!(
                            "{:.precision$} {}",
                            child_byte_filtered.get_value(),
                            child_byte_filtered.get_unit(),
                            precision = args.precision
                        ))
                        .fg(Color::Cyan)
                        .set_alignment(CellAlignment::Right),
                    );
                }

                let disk_usage_byte_filtered =
                    Byte::from_u64(child.blocks_filtered * 512).get_appropriate_unit(unit_type);
                row.push(
                    Cell::new(format!(
                        "{:.precision$} {}",
                        disk_usage_byte_filtered.get_value(),
                        disk_usage_byte_filtered.get_unit(),
                        precision = args.precision
                    ))
                    .fg(Color::Cyan)
                    .set_alignment(CellAlignment::Right),
                );
            }

            row.push(
                Cell::new(child.blocks)
                    .fg(Color::Green)
                    .set_alignment(CellAlignment::Right),
            );

            table.add_row(row);
        } else {
            let mut row = vec![
                Cell::new(name).fg(color),
                Cell::new(&child.entry_type).fg(Color::Yellow),
                Cell::new("N/A")
                    .fg(Color::Red)
                    .set_alignment(CellAlignment::Right),
                Cell::new("Unavailable")
                    .fg(Color::Red)
                    .set_alignment(CellAlignment::Right),
            ];

            if args.compare {
                row.push(
                    Cell::new("-")
                        .fg(Color::Red)
                        .set_alignment(CellAlignment::Right),
                );
                row.push(
                    Cell::new("-")
                        .fg(Color::Red)
                        .set_alignment(CellAlignment::Right),
                );
            }

            row.push(
                Cell::new("-")
                    .fg(Color::Red)
                    .set_alignment(CellAlignment::Right),
            );

            table.add_row(row);
        }
    }
    writeln!(writer, "{table}").ok();
}

fn print_csv(writer: &mut dyn Write, children: &[&Node], args: &Args) {
    let mut wtr = WriterBuilder::new().has_headers(false).from_writer(writer);

    for child in children {
        let mut record = vec![
            child.path.to_string_lossy().to_string(),
            child.entry_type.to_string(),
        ];

        if args.apparent {
            record.push(child.size_bytes.to_string());
        }

        record.push((child.blocks * 512).to_string());
        record.push(child.blocks.to_string());

        wtr.write_record(&record).ok();
    }
    wtr.flush().ok();
}

fn print_json(writer: &mut dyn Write, parent_node: &Node, children: &[&Node], args: &Args) {
    let entries_view: Vec<serde_json::Value> = children
        .iter()
        .map(|c| {
            let mut val = serde_json::json!({
                "path": &c.path,
                "entry_type": c.entry_type.to_string(),
                "accessible": c.accessible,
                "complete": c.complete,
                "hard_link_duplicate": c.hard_link_duplicate,
                "skipped_mount": c.skipped_mount,
                "disk_usage": c.blocks * 512,
                "blocks": c.blocks,
            });

            if args.apparent {
                val.as_object_mut()
                    .unwrap()
                    .insert("apparent_size".to_string(), serde_json::json!(c.size_bytes));
            }

            if args.compare {
                val.as_object_mut().unwrap().insert(
                    "disk_usage_filtered".to_string(),
                    serde_json::json!(c.blocks_filtered * 512),
                );
                val.as_object_mut().unwrap().insert(
                    "blocks_filtered".to_string(),
                    serde_json::json!(c.blocks_filtered),
                );
                if args.apparent {
                    val.as_object_mut().unwrap().insert(
                        "apparent_size_filtered".to_string(),
                        serde_json::json!(c.size_bytes_filtered),
                    );
                }
            }

            val
        })
        .collect();

    let mut report = serde_json::json!({
        "path": &parent_node.path,
        "total_disk_usage": parent_node.blocks * 512,
        "total_blocks": parent_node.blocks,
        "entries": entries_view,
        "accessible": parent_node.accessible,
        "complete": parent_node.complete,
    });

    if args.apparent {
        report.as_object_mut().unwrap().insert(
            "total_apparent".to_string(),
            serde_json::json!(parent_node.size_bytes),
        );
    }

    if args.compare {
        report.as_object_mut().unwrap().insert(
            "total_disk_usage_filtered".to_string(),
            serde_json::json!(parent_node.blocks_filtered * 512),
        );
        report.as_object_mut().unwrap().insert(
            "total_blocks_filtered".to_string(),
            serde_json::json!(parent_node.blocks_filtered),
        );
        if args.apparent {
            report.as_object_mut().unwrap().insert(
                "total_apparent_filtered".to_string(),
                serde_json::json!(parent_node.size_bytes_filtered),
            );
        }
    }

    serde_json::to_writer(&mut *writer, &report).ok();
    writer.write_all(b"\n").ok();
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::fs::File;
    use tempfile::TempDir;

    #[test]
    fn test_parse_sort_arg() {
        let criteria = parse_sort_arg("size:asc,name");
        assert_eq!(criteria.len(), 2);
        assert_eq!(criteria[0], (SortColumn::Disk, SortDirection::Asc));
        assert_eq!(criteria[1], (SortColumn::Name, SortDirection::Asc)); // Default for Name is Asc
    }

    #[test]
    fn test_sort_defaults() {
        let criteria = parse_sort_arg("size");
        assert_eq!(criteria[0], (SortColumn::Disk, SortDirection::Dsc)); // Default for Size is Dsc
    }

    #[test]
    fn test_build_tree() {
        let temp_dir = TempDir::new().unwrap();
        let file_path = temp_dir.path().join("test_file.txt");
        File::create(&file_path)
            .unwrap()
            .write_all(b"Hello")
            .unwrap();

        let node = build_tree(temp_dir.path(), false, false);

        assert_eq!(node.entry_type, EntryType::Dir);
        assert!(!node.children.is_empty());
        assert_eq!(node.children[0].path, file_path);
        // Size should be at least 5 bytes
        assert!(node.children[0].size_bytes >= 5);
    }
}