package cobra

import (

	"bytes"

	"fmt"

	"io"

	"os"

	"strings"

)

func genFishComp(buf io.StringWriter, name string, includeDesc bool) {

	// Variables should not contain a '-' or ':' character

	nameForVar := name

	compCmd := ShellCompRequestCmd

	if !includeDesc {

		compCmd = ShellCompNoDescRequestCmd

	}

	WriteStringAndCheck(buf, fmt.Sprintf("# fish completion for %-36s -*- shell-script -*-\n", name))

	WriteStringAndCheck(buf, fmt.Sprintf(`

function __%[1]s_debug

    set -l file "$BASH_COMP_DEBUG_FILE"

    if test -n "$file"

        echo "$argv" >> $file

    end

end

function __%[1]s_perform_completion

    __%[1]s_debug "Starting __%[1]s_perform_completion"

    # Extract all args except the last one

    set -l args (commandline -opc)

    # Extract the last arg and escape it in case it is a space

    set -l lastArg (string escape -- (commandline -ct))

    __%[1]s_debug "args: $args"

    __%[1]s_debug "last arg: $lastArg"

    __%[1]s_debug "Calling $requestComp"

    set -l results (eval $requestComp 2> /dev/null)

    # Some programs may output extra empty lines after the directive.

    # Let's ignore them or else it will break completion.

    # Ref: https://github.com/spf13/cobra/issues/1279

    for line in $results[-1..1]

        if test (string trim -- $line) = ""

            # Found an empty line, remove it

            set results $results[1..-2]

        else

            # Found non-empty line, we have our proper output

            break

        end

    end

    set -l comps $results[1..-2]

    set -l directiveLine $results[-1]

    # For Fish, when completing a flag with an = (e.g., <program> -n=<TAB>)

    # completions must be prefixed with the flag

    set -l flagPrefix (string match -r -- '-.*=' "$lastArg")

    __%[1]s_debug "Comps: $comps"

    __%[1]s_debug "DirectiveLine: $directiveLine"

    __%[1]s_debug "flagPrefix: $flagPrefix"

    for comp in $comps

        printf "%%s%%s\n" "$flagPrefix" "$comp"

    end

    printf "%%s\n" "$directiveLine"

end

# This function does two things:

# - Obtain the completions and store them in the global __%[1]s_comp_results

# - Return false if file completion should be performed

function __%[1]s_prepare_completions

    __%[1]s_debug ""

    __%[1]s_debug "========= starting completion logic =========="

    # Start fresh

    set --erase __%[1]s_comp_results

    set -l results (__%[1]s_perform_completion)

    __%[1]s_debug "Completion results: $results"

    if test -z "$results"

        __%[1]s_debug "No completion, probably due to a failure"

        # Might as well do file completion, in case it helps

        return 1

    end

    set -l directive (string sub --start 2 $results[-1])

    set --global __%[1]s_comp_results $results[1..-2]

    __%[1]s_debug "Completions are: $__%[1]s_comp_results"

    __%[1]s_debug "Directive is: $directive"

    set -l shellCompDirectiveError %[4]d

    set -l shellCompDirectiveNoSpace %[5]d

    set -l shellCompDirectiveNoFileComp %[6]d

    set -l shellCompDirectiveFilterFileExt %[7]d

    set -l shellCompDirectiveFilterDirs %[8]d

    if test -z "$directive"

        set directive 0

    end

    set -l compErr (math (math --scale 0 $directive / $shellCompDirectiveError) %% 2)

    if test $compErr -eq 1

        __%[1]s_debug "Received error directive: aborting."

        # Might as well do file completion, in case it helps

        return 1

    end

    set -l filefilter (math (math --scale 0 $directive / $shellCompDirectiveFilterFileExt) %% 2)

    set -l dirfilter (math (math --scale 0 $directive / $shellCompDirectiveFilterDirs) %% 2)

    if test $filefilter -eq 1; or test $dirfilter -eq 1

        __%[1]s_debug "File extension filtering or directory filtering not supported"

        # Do full file completion instead

        return 1

    end

    set -l nospace (math (math --scale 0 $directive / $shellCompDirectiveNoSpace) %% 2)

    set -l nofiles (math (math --scale 0 $directive / $shellCompDirectiveNoFileComp) %% 2)

    __%[1]s_debug "nospace: $nospace, nofiles: $nofiles"

    # If we want to prevent a space, or if file completion is NOT disabled,

    # we need to count the number of valid completions.

    # To do so, we will filter on prefix as the completions we have received

    # may not already be filtered so as to allow fish to match on different

    # criteria than the prefix.

    if test $nospace -ne 0; or test $nofiles -eq 0

        set -l prefix (commandline -t | string escape --style=regex)

        __%[1]s_debug "prefix: $prefix"

        set -l completions (string match -r -- "^$prefix.*" $__%[1]s_comp_results)

        set --global __%[1]s_comp_results $completions

        __%[1]s_debug "Filtered completions are: $__%[1]s_comp_results"

        # Important not to quote the variable for count to work

        set -l numComps (count $__%[1]s_comp_results)

        __%[1]s_debug "numComps: $numComps"

        if test $numComps -eq 1; and test $nospace -ne 0

            # We must first split on \t to get rid of the descriptions to be

            # able to check what the actual completion will be.

            # We don't need descriptions anyway since there is only a single

            # real completion which the shell will expand immediately.

            set -l split (string split --max 1 \t $__%[1]s_comp_results[1])

            # Fish won't add a space if the completion ends with any

            # of the following characters: @=/:.,

            set -l lastChar (string sub -s -1 -- $split)

            if not string match -r -q "[@=/:.,]" -- "$lastChar"

                # In other cases, to support the "nospace" directive we trick the shell

                # by outputting an extra, longer completion.

                __%[1]s_debug "Adding second completion to perform nospace directive"

                set --global __%[1]s_comp_results $split[1] $split[1].

                __%[1]s_debug "Completions are now: $__%[1]s_comp_results"

            end

        end

        if test $numComps -eq 0; and test $nofiles -eq 0

            # To be consistent with bash and zsh, we only trigger file

            # completion when there are no other completions

            __%[1]s_debug "Requesting file completion"

            return 1

        end

    end

    return 0

end

# Since Fish completions are only loaded once the user triggers them, we trigger them ourselves

# so we can properly delete any completions provided by another script.

# Only do this if the program can be found, or else fish may print some errors; besides,

# the existing completions will only be loaded if the program can be found.

if type -q "%[2]s"

    # The space after the program name is essential to trigger completion for the program

    # and not completion of the program name itself.

    # Also, we use '> /dev/null 2>&1' since '&>' is not supported in older versions of fish.

    complete --do-complete "%[2]s " > /dev/null 2>&1

end

# Remove any pre-existing completions for the program since we will be handling all of them.

complete -c %[2]s -e

# The call to __%[1]s_prepare_completions will setup __%[1]s_comp_results

# which provides the program's completion choices.

complete -c %[2]s -n '__%[1]s_prepare_completions' -f -a '$__%[1]s_comp_results'

`, nameForVar, name, compCmd,

		ShellCompDirectiveError, ShellCompDirectiveNoSpace, ShellCompDirectiveNoFileComp,

}

// GenFishCompletion generates fish completion file and writes to the passed writer.

func (c *Command) GenFishCompletion(w io.Writer, includeDesc bool) error {

	buf := new(bytes.Buffer)

	genFishComp(buf, c.Name(), includeDesc)

	_, err := buf.WriteTo(w)

	return err

}

// GenFishCompletionFile generates fish completion file.

func (c *Command) GenFishCompletionFile(filename string, includeDesc bool) error {

	outFile, err := os.Create(filename)

	if err != nil {

		return err

	}

	defer outFile.Close()

	return c.GenFishCompletion(outFile, includeDesc)

}