//! `koh man` — the manual, built into the binary.
//!
//! The page lives in `docs/koh3-man.txt` and is embedded at build time, so a
//! `koh` copied to another machine still carries its own documentation. With a
//! command name it prints just that command's part; otherwise the whole page,
//! through the built-in pager on a terminal.

module cli

import os
import src.fmt
import src.view

const manual = $embed_file('../../docs/koh3-man.txt').to_string()

pub fn cmd_man(raw []string) int {
	args := parse('man', raw, Options{}) or { return usage_error(err.msg()) }
	mut text := manual
	if args.positional.len > 0 {
		name := args.positional_at(0)
		text = section_of(name) or {
			eprintln('  ${fmt.red(fmt.glyph_fail)} the manual has no "${name}" — try "koh man" for the whole page')
			return 2
		}
	}
	page(text)
	return 0
}

// section_of returns one command's entry from the COMMANDS section: its
// synopsis lines, which may name several commands, down to the next entry.
fn section_of(name string) ?string {
	lines := manual.split_into_lines()
	mut start := -1
	mut in_commands := false
	for i, line in lines {
		if line == 'COMMANDS' {
			in_commands = true
		} else if in_commands && is_synopsis(line)
			&& (line.starts_with('    koh ${name} ') || line == '    koh ${name}') {
			start = i
			break
		}
	}
	if start < 0 {
		return none
	}
	for start > 0 && is_synopsis(lines[start - 1]) {
		start--
	}
	mut end := start
	for end < lines.len && is_synopsis(lines[end]) {
		end++
	}
	// The body is indented eight columns; anything shallower starts the next
	// entry, group or section.
	for end < lines.len && (lines[end] == '' || lines[end].starts_with('        ')) {
		end++
	}
	return lines[start..end].join('\n').trim_right('\n ')
}

fn is_synopsis(line string) bool {
	return line.starts_with('    koh ')
}

// page shows the manual in Koh 2's colours, through the built-in pager when it
// is longer than the terminal, and plainly when the output is going somewhere
// else.
fn page(text string) {
	lines := text.trim_right('\n').split_into_lines().map(manual_line(it))
	rows, _ := view.terminal_size()
	if os.is_atty(1) != 0 && os.is_atty(0) != 0 && lines.len >= rows {
		view.page_manual(lines)
		return
	}
	for line in lines {
		println(line.text)
	}
}

// manual_line colours one line as Koh 2's `colorManLine` does: headings blue
// behind a ◆, command lines amber, lead-ins ending in a colon orange, and body
// text light with its `--flags` picked out.
fn manual_line(line string) view.ManualLine {
	trimmed := line.trim_left(' ')
	if line != '' && !line.starts_with(' ') && line == line.to_upper() {
		return view.ManualLine{
			text:    if fmt.colour_enabled() { fmt.blue('◆ ${line}') } else { line }
			section: line
		}
	}
	if trimmed.starts_with('koh ') {
		return view.ManualLine{
			text: fmt.gold(line)
		}
	}
	if trimmed != line && trimmed.ends_with(':') {
		return view.ManualLine{
			text: fmt.warning(line)
		}
	}
	return view.ManualLine{
		text: line[..line.len - trimmed.len] + body_text(trimmed)
	}
}

// body_text paints body text light, with each `--flag` in it amber.
fn body_text(text string) string {
	mut out := ''
	mut rest := text
	for {
		at := rest.index('--') or { break }
		mut end := at + 2
		for end < rest.len && rest[end] !in [` `, `,`, `)`, `.`, `\``] {
			end++
		}
		if end == at + 2 {
			out += fmt.light(rest[..end])
		} else {
			out += fmt.light(rest[..at]) + fmt.gold(rest[at..end])
		}
		rest = rest[end..]
	}
	return out + fmt.light(rest)
}