function __fish_opam_using_command
    set cmd (commandline -opc)
    if [ (count $cmd) -gt 1 ]
        if [ $argv[1] = $cmd[2] ]
            return 0
        end
    end
    return 1
end

function __fish_opam_at_color
    set cmd (commandline -opc)
    if [ (count $cmd) -gt 2 ]
        if [ $cmd[-1] = '--color' ]
            return 0
        end
    end
    return 1
end

function __fish_opam_needs_command
    set cmd (commandline -opc)
    if [ (count $cmd) -eq 1 ]
        return 0
    end
    return 1
end

# general flags
## ones that work without any subcommand
complete -f -c opam -l 'help' -d "Display the manual for an OPAM command."
complete -f -c opam -l version -d 'Show version information.'
## ones that require at least a subcommand (but are shared by all)
### colour
complete -f -c opam -n 'not __fish_opam_needs_command' -l color -d 'Colorize the output.  WHEN must be `always\', `never\' or `auto\'.'
complete -f -c opam -n '__fish_opam_at_color' -a 'always never auto'
### rest
complete -f -c opam -n 'not __fish_opam_needs_command' -l 'compat-mode-1.0' -d 'Compatibility mode with OPAM 1.0'
complete -f -c opam -n 'not __fish_opam_needs_command' -l debug -d 'Print debug message on stdout.'
complete -f -c opam -n 'not __fish_opam_needs_command' -l git-version -d 'Print the git version if it exists and exit.'
complete -f -c opam -n 'not __fish_opam_needs_command' -l no-aspcud -d 'Do not use the external aspcud solver, even if available.'
complete -f -c opam -n 'not __fish_opam_needs_command' -l no-base-packages -d 'Do not install base packages (useful for testing purposes).'
complete -f -c opam -n 'not __fish_opam_needs_command' -s q -l quiet -d 'Be quiet when installing a new compiler.'
complete -f -c opam -n 'not __fish_opam_needs_command' -s r -l root -d 'Use ROOT as the current root path.'
complete -f -c opam -n 'not __fish_opam_needs_command' -l strict -d 'Fail whenever an error is found in a package definition or a configuration file. The default is to continue silently if possible.'
complete -f -c opam -n 'not __fish_opam_needs_command' -l switch -d 'Use SWITCH as the current compiler switch.'
complete -f -c opam -n 'not __fish_opam_needs_command' -s v -l verbose -d 'Be more verbose.'
complete -f -c opam -n 'not __fish_opam_needs_command' -s y -l yes -d 'Disable interactive mode and answer yes to all questions that would otherwise be asked to the user.'

# subcommands
## config
complete -f -c opam -n '__fish_opam_needs_command' -a config -d "Display configuration options for packages."
### config flags
complete -f -c opam -n '__fish_opam_using_command config' -s a -l all -d 'Enable all the global and user configuration options.'
complete -f -c opam -n '__fish_opam_using_command config' -l csh -d 'Use csh-compatible mode for configuring OPAM.'
complete -f -c opam -n '__fish_opam_using_command config' -l dot-profile -d 'Name of the configuration file to update instead of ~/.'
complete -f -c opam -n '__fish_opam_using_command config' -s e -d 'Backward-compatible option, equivalent to opam config env.'
complete -f -c opam -n '__fish_opam_using_command config' -l fish -d 'Use fish-compatible mode for configuring OPAM.'
complete -f -c opam -n '__fish_opam_using_command config' -s g -l global -d 'Enable all the global configuration options.'
complete -f -c opam -n '__fish_opam_using_command config' -s l -l list -d 'List the current configuration.'
complete -f -c opam -n '__fish_opam_using_command config' -l no-complete -d 'Do not load the auto-completion scripts in the environment.'
complete -f -c opam -n '__fish_opam_using_command config' -l no-switch-eval -d 'Do not install `opam-switch-eval` to switch & e… [See Man Page]'
complete -f -c opam -n '__fish_opam_using_command config' -l ocamlinit -d 'Modify ~/.'
complete -f -c opam -n '__fish_opam_using_command config' -l profile -d 'Modify ~/. profile (or ~/.'
complete -f -c opam -n '__fish_opam_using_command config' -s R -l rec -d 'Recursive query.'
complete -f -c opam -n '__fish_opam_using_command config' -l sexp -d 'Display environment variables as an s-expression.'
complete -f -c opam -n '__fish_opam_using_command config' -l sh -d 'Use sh-compatible mode for configuring OPAM.'
complete -f -c opam -n '__fish_opam_using_command config' -s u -l user -d 'Enable all the user configuration options.'
complete -f -c opam -n '__fish_opam_using_command config' -l zsh -d 'Use zsh-compatible mode for configuring OPAM.  DOMAINS.'
### config subcommands
complete -f -c opam -n '__fish_opam_using_command config' -a env -d 'Return the environment variables PATH, MANPATH, OCAML_TOPLEVEL_PATH and CAML_LD_LIBRARY_PATH according to the currently selected compiler.'
complete -f -c opam -n '__fish_opam_using_command config' -a setup -d 'Configure global and user parameters for OPAM. [see manpage]' #TODO
complete -f -c opam -n '__fish_opam_using_command config' -a exec -d 'Execute the shell script given in parameter with the correct environment variables. [see manpage]'
complete -f -c opam -n '__fish_opam_using_command config' -a var -d 'Return the value associated with the given variable. [see manpage]'
complete -f -c opam -n '__fish_opam_using_command config' -a list -d 'Return the list of all variables defined in the listed packages. [see manpage]'
complete -f -c opam -n '__fish_opam_using_command config' -a subst -d 'Substitute variables in the given files. The strings %{var}% are replaced by the value of the variable var [see manpage]'
complete -f -c opam -n '__fish_opam_using_command config' -a includes -d 'returns include options.'
complete -f -c opam -n '__fish_opam_using_command config' -a bytecomp -d 'returns bytecode compile options.'
complete -f -c opam -n '__fish_opam_using_command config' -a asmcomp -d 'returns assembly compile options.'
complete -f -c opam -n '__fish_opam_using_command config' -a bytelink -d 'returns bytecode linking options.'
complete -f -c opam -n '__fish_opam_using_command config' -a report -d 'Prints a summary of your setup, useful for bug-reports.'

# TODO all subcommands other than config (and admin?)
complete -f -c opam -n '__fish_opam_needs_command' -a "help" -d "Display help about OPAM and OPAM commands."
complete -f -c opam -n '__fish_opam_needs_command' -a "init" -d "Initialize OPAM state."
complete -f -c opam -n '__fish_opam_needs_command' -a "install" -d "Install a list of packages."
complete -f -c opam -n '__fish_opam_needs_command' -a "list" -d "Display the list of available packages."
complete -f -c opam -n '__fish_opam_needs_command' -a "pin" -d "Pin a given package to a specific version."
complete -f -c opam -n '__fish_opam_needs_command' -a "reinstall" -d "Reinstall a list of packages."
complete -f -c opam -n '__fish_opam_needs_command' -a "remove uninstall" -d "Remove a list of packages."
complete -f -c opam -n '__fish_opam_needs_command' -a "repository remote" -d "Manage OPAM repositories."
complete -f -c opam -n '__fish_opam_needs_command' -a "search" -d "Search into the package list."
complete -f -c opam -n '__fish_opam_needs_command' -a "show info" -d "Display information about specific packages."
complete -f -c opam -n '__fish_opam_needs_command' -a "switch" -d "Manage multiple installation of compilers."
complete -f -c opam -n '__fish_opam_needs_command' -a "update" -d "Update the list of available packages."
complete -f -c opam -n '__fish_opam_needs_command' -a "upgrade" -d "Upgrade the installed package to latest version."
## admin
complete -f -c opam -n '__fish_opam_needs_command' -a "admin" -d "Administration tool for local repositories."
complete -c opam -n '__fish_opam_using_command admin' -l 'help' -d 'Show this help in format FMT (pager, plain or groff).'
complete -c opam -n '__fish_opam_using_command admin' -l 'version' -d 'Show version information.'
complete -f -c opam -n '__fish_opam_using_command admin' -a "check" -d "Check a local repo for errors."
complete -f -c opam -n '__fish_opam_using_command admin' -a "depexts" -d "Add external dependencies."
complete -f -c opam -n '__fish_opam_using_command admin' -a "make" -d "Initialize a repo for serving files."
complete -f -c opam -n '__fish_opam_using_command admin' -a "stats" -d "Compute statistics."