powerline_venv_prompt.lua

-- Source: https://github.com/Tset-Noitamotua/cmder-powerline-venv-prompt/

-- Resets the prompt 
function lambda_prompt_filter()
    cwd = clink.get_cwd()
    prompt = "\x1b[37;44m{cwd} {git}{hg}\n\x1b[1;30;40m{lamb} \x1b[0m"
    new_value = string.gsub(prompt, "{cwd}", cwd)
    clink.prompt.value = string.gsub(new_value, "{lamb}", "λ")
end

--- copied from clink.lua
 -- Resolves closest directory location for specified directory.
 -- Navigates subsequently up one level and tries to find specified directory
 -- @param  {string} path    Path to directory will be checked. If not provided
 --                          current directory will be used
 -- @param  {string} dirname Directory name to search for
 -- @return {string} Path to specified directory or nil if such dir not found
local function get_dir_contains(path, dirname)

    -- return parent path for specified entry (either file or directory)
    local function pathname(path)
        local prefix = ""
        local i = path:find("[\\/:][^\\/:]*$")
        if i then
            prefix = path:sub(1, i-1)
        end
        return prefix
    end

    -- Navigates up one level
    local function up_one_level(path)
        if path == nil then path = '.' end
        if path == '.' then path = clink.get_cwd() end
        return pathname(path)
    end

    -- Checks if provided directory contains git directory
    local function has_specified_dir(path, specified_dir)
        if path == nil then path = '.' end
        local found_dirs = clink.find_dirs(path..'/'..specified_dir)
        if #found_dirs > 0 then return true end
        return false
    end

    -- Set default path to current directory
    if path == nil then path = '.' end

    -- If we're already have .git directory here, then return current path
    if has_specified_dir(path, dirname) then
        return path..'/'..dirname
    else
        -- Otherwise go up one level and make a recursive call
        local parent_path = up_one_level(path)
        if parent_path == path then
            return nil
        else
            return get_dir_contains(parent_path, dirname)
        end
    end
end

-- copied from clink.lua
-- clink.lua is saved under %CMDER_ROOT%\vendor
local function get_hg_dir(path)
    return get_dir_contains(path, '.hg')
end

-- adopted from clink.lua
-- clink.lua is saved under %CMDER_ROOT%\vendor
function colorful_hg_prompt_filter()

    -- Colors for mercurial status
    local colors = {
        clean = "\x1b[1;37;40m",
        dirty = "\x1b[31;1m",
    }

    if get_hg_dir() then
        -- if we're inside of mercurial repo then try to detect current branch
        local branch = get_hg_branch()
        if branch then
            -- Has branch => therefore it is a mercurial folder, now figure out status
            if get_hg_status() then
                color = colors.clean
            else
                color = colors.dirty
            end

            clink.prompt.value = string.gsub(clink.prompt.value, "{hg}", color.."("..branch..")")
            return false
        end
    end

    -- No mercurial present or not in mercurial file
    clink.prompt.value = string.gsub(clink.prompt.value, "{hg}", "")
    return false
end

-- copied from clink.lua
-- clink.lua is saved under %CMDER_ROOT%\vendor
local function get_git_dir(path)

    -- return parent path for specified entry (either file or directory)
    local function pathname(path)
        local prefix = ""
        local i = path:find("[\\/:][^\\/:]*$")
        if i then
            prefix = path:sub(1, i-1)
        end
        return prefix
    end

    -- Checks if provided directory contains git directory
    local function has_git_dir(dir)
        return #clink.find_dirs(dir..'/.git') > 0 and dir..'/.git'
    end

    local function has_git_file(dir)
        local gitfile = io.open(dir..'/.git')
        if not gitfile then return false end

        local git_dir = gitfile:read():match('gitdir: (.*)')
        gitfile:close()

        return git_dir and dir..'/'..git_dir
    end

    -- Set default path to current directory
    if not path or path == '.' then path = clink.get_cwd() end

    -- Calculate parent path now otherwise we won't be
    -- able to do that inside of logical operator
    local parent_path = pathname(path)

    return has_git_dir(path)
        or has_git_file(path)
        -- Otherwise go up one level and make a recursive call
        or (parent_path ~= path and get_git_dir(parent_path) or nil)
end

---
 -- Get the status of working dir
 -- @return {bool}
---
function get_git_status()
    return os.execute("git diff --quiet --ignore-submodules HEAD")
end

-- adopted from clink.lua
-- Modified to add colors and arrow symbols
function colorful_git_prompt_filter()

    -- Colors for git status
    local colors = {
        clean = "\x1b[34;42m\x1b[37;42m ",
        dirty = "\x1b[34;43m\x1b[30;43m ",
    }

    local closingcolors = {
        clean = " \x1b[32;40m",
        dirty = "± \x1b[33;40m",
    }

    local git_dir = get_git_dir()
    if git_dir then
        -- if we're inside of git repo then try to detect current branch
        local branch = get_git_branch(git_dir)
        if branch then
            -- Has branch => therefore it is a git folder, now figure out status
            if get_git_status() then
                color = colors.clean
                closingcolor = closingcolors.clean
            else
                color = colors.dirty
                closingcolor = closingcolors.dirty
            end

            clink.prompt.value = string.gsub(clink.prompt.value, "{git}", color.."  "..branch..closingcolor)
            return false
        end
    end

    -- No git present or not in git file
    clink.prompt.value = string.gsub(clink.prompt.value, "{git}", "\x1b[34;40m")
    return false
end



function get_virtual_env(env_var)
    env_path = clink.get_env(env_var)
    if env_path then
        basen = exports.basename(env_path)
        return basen
    end
    return false
end

---
 -- add python virutual env name 
---
function conda_prompt_filter()
    -- add in python virtual env name
    local python_env = get_virtual_env('DEFAULT_ENV')
    if python_env then
        clink.prompt.value = string.gsub(clink.prompt.value, "λ", "["..python_env.."] λ")
    end
end

---
 -- add virtual env name 
---
function venv_prompt_filter()
    -- add in virtual env name
    local venv = get_virtual_env('VIRTUAL_ENV')
    if venv then
        clink.prompt.value = string.gsub(clink.prompt.value, "λ", "["..venv.."] λ")
    end
end

-- override the built-in filters
clink.prompt.register_filter(conda_prompt_filter, 20)
clink.prompt.register_filter(lambda_prompt_filter, 55)
clink.prompt.register_filter(colorful_hg_prompt_filter, 60)
clink.prompt.register_filter(colorful_git_prompt_filter, 60)
clink.prompt.register_filter(venv_prompt_filter, 65)