import type { CommandFlag, CommandSpec } from 'lib/commands/spec.js'

import { describeForShell } from './describe.js'

export const renderFishCompletion = (spec: CommandSpec): string =>
  `${[
    header,
    helpers,
    ['complete -c seam -f', ...subcommandCompletions(spec)].join('\n'),
    flagCompletions(spec).join('\n'),
    globalFlagCompletions(spec).join('\n'),
  ].join('\n\n')}\n`

const header = `# fish completion for the seam command.
#
# Generated by @seamapi/cli from the Seam API schema.
# Do not edit: regenerate with 'seam completion fish'.
#
# Install it with
#
#   seam completion fish > ~/.config/fish/completions/seam.fish`

const helpers = `function __seam_command --description 'Print the seam command path on the command-line'
    set -l tokens (commandline -opc)
    set -l command
    if test (count $tokens) -gt 1
        # The command path is the run of words before the first flag.
        for token in $tokens[2..-1]
            if string match -q -- '-*' $token
                break
            end
            set -a command $token
        end
    end
    string join ' ' -- $command
end

function __seam_using --description 'Test whether the command-line names the given seam command'
    set -l command (__seam_command)
    test "$command" = "$argv[1]"
end`

const subcommandCompletions = (spec: CommandSpec): string[] =>
  spec.groups.flatMap((group) =>
    group.subcommands.map(({ name, description }) =>
      complete([
        `-n '__seam_using "${group.path.join(' ')}"'`,
        `-a '${name}'`,
        describe(description),
      ]),
    ),
  )

const flagCompletions = (spec: CommandSpec): string[] =>
  spec.commands.flatMap((command) =>
    command.flags.map((flag) =>
      complete([
        `-n '__seam_using "${command.path.join(' ')}"'`,
        ...flagOptions(flag),
      ]),
    ),
  )

const globalFlagCompletions = (spec: CommandSpec): string[] =>
  spec.globalFlags.map((flag) => complete(flagOptions(flag)))

const flagOptions = (flag: CommandFlag): string[] => [
  ...(flag.short == null ? [] : [`-s ${flag.short}`]),
  ...(flag.long == null ? [] : [`-l ${flag.long}`]),
  ...(flag.takesValue ? ['-r'] : []),
  ...(flag.values.length === 0 ? [] : [`-a '${flag.values.join(' ')}'`]),
  describe(flag.description),
]

const describe = (description: string): string => {
  const summary = describeForShell(description)
  return summary === '' ? '' : `-d '${summary}'`
}

const complete = (options: string[]): string =>
  ['complete -c seam', ...options.filter((option) => option !== '')].join(' ')