module pref

import os

// Preferences represents preferences data used by pref.
pub struct Preferences {
pub mut:
    verbose      bool
    output_file  string
    target_os    string = os.user_os()
    user_defines []string
    backend      string = 'c'
    c99          bool
    vroot        string = detect_vroot()
    selfhost     bool
    building_v   bool // compiling the V compiler itself: no generics, skip monomorphization
}

// new_preferences supports new preferences handling for pref.
pub fn new_preferences() &Preferences {
    return &Preferences{}
}

// detect_vroot resolves detect vroot information for pref.
fn detect_vroot() string {
    baked_root := @VMODROOT
    if baked_root.len > 0 {
        return baked_root
    }
    if os.args.len > 0 && os.args[0].len > 0 {
        vroot := detect_vroot_from(os.args[0])
        if vroot.len > 0 {
            return vroot
        }
    }
    return detect_vroot_from(os.getwd())
}

// detect_vroot_from resolves detect vroot from information for pref.
fn detect_vroot_from(start string) string {
    if start.len == 0 {
        return ''
    }
    mut dir := start
    if !os.is_abs_path(dir) {
        cwd := os.getwd()
        if cwd.len > 0 {
            dir = os.join_path_single(cwd, dir)
        }
    }
    if !os.is_dir(dir) {
        dir = os.dir(dir)
    }
    for _ in 0 .. 8 {
        if os.is_dir(os.join_path_single(os.join_path_single(dir, 'vlib'), 'builtin')) {
            return dir
        }
        parent := os.dir(dir)
        if parent == dir {
            break
        }
        dir = parent
    }
    return ''
}

// get_vlib_module_path returns get vlib module path data for Preferences.
pub fn (p &Preferences) get_vlib_module_path(mod string) string {
    mod_path := mod.replace('.', os.path_separator)
    return os.join_path_single(os.join_path_single(p.vroot, 'vlib'), mod_path)
}

// get_module_path returns get module path data for Preferences.
pub fn (p &Preferences) get_module_path(mod string, importing_file_path string) string {
    mod_path := mod.replace('.', os.path_separator)
    // Absolutize the importer like V1's Builder.find_module_path does
    // (`os.real_path(fpath)`). When the input is given as a relative path (e.g.
    // `v3 -o out .`), the parsed file paths are relative too (`./doka.v`), and a
    // parent-directory walk starting from `.` could never climb above the project
    // dir to find sibling modules.
    abs_importer := os.real_path(importing_file_path)
    importer_dir := os.dir(abs_importer)
    // 1. relative to the importing file's directory
    relative_path := os.join_path_single(importer_dir, mod_path)
    if dir_is_module(relative_path) {
        return relative_path
    }
    // 2. vlib
    vlib_path := os.join_path_single(os.join_path_single(p.vroot, 'vlib'), mod_path)
    if dir_is_module(vlib_path) {
        return vlib_path
    }
    // 3. ~/.vmodules (or $VMODULES)
    vmodules_path := os.join_path_single(vmodules_dir(), mod_path)
    if dir_is_module(vmodules_path) {
        return vmodules_path
    }
    // 4. walk up the parent directories of the importing file, like V1's
    // Builder.find_module_path. This finds sibling projects: e.g. importing
    // `viper` from ~/code/doka/doka.v resolves to ~/code/viper.
    mut current_dir := importer_dir
    for {
        try_path := os.join_path_single(current_dir, mod_path)
        if dir_is_module(try_path) {
            return try_path
        }
        parent_dir := os.dir(current_dir)
        if parent_dir == current_dir {
            break
        }
        current_dir = parent_dir
    }
    return ''
}

// dir_is_module reports whether `dir` is a usable module directory: it must exist
// and contain at least one `.v` source file. V1 applies the same `.v`-files guard
// (`module_path_has_v_files`); without it the parent-directory walk could match an
// unrelated directory that merely shares a module's name (e.g. `~/code/util`),
// shadowing the real module.
fn dir_is_module(dir string) bool {
    if dir.len == 0 || !os.is_dir(dir) {
        return false
    }
    entries := os.ls(dir) or { return false }
    for entry in entries {
        if entry.ends_with('.v') {
            return true
        }
    }
    return false
}

// vmodules_dir returns the user's global modules directory ($VMODULES or ~/.vmodules).
fn vmodules_dir() string {
    env_dir := os.getenv('VMODULES')
    if env_dir.len > 0 {
        return env_dir
    }
    return os.join_path_single(os.home_dir(), '.vmodules')
}

// file_has_incompatible_os_suffix converts file has incompatible os suffix data for pref.
pub fn file_has_incompatible_os_suffix(file string, current_os string) bool {
    os_name := normalized_os(current_os)
    if os_name == 'windows' && file.contains('_nix.') {
        return true
    }
    if os_name != 'windows' && file.contains('_windows.') {
        return true
    }
    if os_name != 'linux' && file.contains('_linux.') {
        return true
    }
    if os_name != 'macos' && (file.contains('_macos.') || file.contains('_darwin.')) {
        return true
    }
    if os_name != 'macos' && os_name != 'freebsd' && os_name != 'openbsd' && os_name != 'netbsd'
        && os_name != 'dragonfly' && file.contains('_bsd.') {
        return true
    }
    if os_name != 'android' && file.contains('_android') {
        return true
    }
    if os_name != 'ios' && file.contains('_ios.') {
        return true
    }
    if os_name != 'freebsd' && file.contains('_freebsd.') {
        return true
    }
    if os_name != 'openbsd' && file.contains('_openbsd.') {
        return true
    }
    if os_name != 'netbsd' && file.contains('_netbsd.') {
        return true
    }
    if os_name != 'dragonfly' && file.contains('_dragonfly.') {
        return true
    }
    if os_name != 'solaris' && file.contains('_solaris.') {
        return true
    }
    if file.contains('.amd64.') || file.contains('_amd64.') || file.contains('.arm64.')
        || file.contains('_arm64.') {
        return true
    }
    return false
}

// get_v_files_from_dir returns get v files from dir data for pref.
pub fn get_v_files_from_dir(dir string, user_defines []string, target_os string) []string {
    if dir == '' || !os.is_dir(dir) {
        return []string{}
    }
    all_files := os.ls(dir) or { return []string{} }
    mut has_os_specific := map[string]bool{}
    for file in all_files {
        if !file.ends_with('.v') || file.ends_with('.js.v') || file.contains('_test.') {
            continue
        }
        if file_has_incompatible_os_suffix(file, target_os) {
            continue
        }
        if base := os_specific_base(file, target_os) {
            has_os_specific[base] = true
        }
    }
    mut v_files := []string{}
    for file in all_files {
        if !file.ends_with('.v') || file.ends_with('.js.v') || file.contains('_test.') {
            continue
        }
        if file_has_incompatible_os_suffix(file, target_os) {
            continue
        }
        if base := default_file_base(file) {
            if has_os_specific[base] {
                continue
            }
        }
        if file.contains('_notd_') {
            feature := extract_define_feature(file, '_notd_')
            if feature.len > 0 && feature in user_defines {
                continue
            }
        } else if file.contains('_d_') {
            feature := extract_define_feature(file, '_d_')
            if feature.len == 0 || feature !in user_defines {
                continue
            }
        }
        v_files << os.join_path_single(dir, file)
    }
    return v_files
}

pub fn is_test_file_for_backend(path string, backend string) bool {
    file := os.file_name(path)
    if file.ends_with('_test.v') {
        return true
    }
    if file.ends_with('_test.c.v') {
        return backend == 'c'
    }
    if file.ends_with('_test.js.v') {
        return backend == 'js'
    }
    if !file.ends_with('.v') {
        return false
    }
    base := file[..file.len - 2]
    if !base.contains('.') {
        return false
    }
    backend_suffix := base.all_after_last('.')
    test_base := base.all_before_last('.')
    if !test_base.ends_with('_test') {
        return false
    }
    return backend_suffix == backend
}

// default_file_base supports default file base handling for pref.
fn default_file_base(file string) ?string {
    for marker in ['_default.c.v', '_default.v'] {
        if file.ends_with(marker) {
            return file[..file.len - marker.len]
        }
    }
    return none
}

// os_specific_base supports os specific base handling for pref.
fn os_specific_base(file string, target_os string) ?string {
    if _ := default_file_base(file) {
        return none
    }
    mut suffixes := []string{}
    os_name := normalized_os(target_os)
    if os_name != 'windows' {
        suffixes << '_nix'
    }
    match os_name {
        'windows' {
            suffixes << '_windows'
        }
        'macos' {
            suffixes << '_macos'
            suffixes << '_darwin'
        }
        'linux' {
            suffixes << '_linux'
        }
        'android' {
            suffixes << '_android'
        }
        'ios' {
            suffixes << '_ios'
        }
        'freebsd' {
            suffixes << '_freebsd'
            suffixes << '_bsd'
        }
        'openbsd' {
            suffixes << '_openbsd'
            suffixes << '_bsd'
        }
        'netbsd' {
            suffixes << '_netbsd'
            suffixes << '_bsd'
        }
        'dragonfly' {
            suffixes << '_dragonfly'
            suffixes << '_bsd'
        }
        'solaris' {
            suffixes << '_solaris'
        }
        else {}
    }

    for suffix in suffixes {
        for ext in ['.c.v', '.v'] {
            marker := suffix + ext
            if file.ends_with(marker) {
                return file[..file.len - marker.len]
            }
        }
    }
    return none
}

// extract_define_feature supports extract define feature handling for pref.
fn extract_define_feature(file string, marker string) string {
    idx := file.index(marker) or { return '' }
    rest := file[idx + marker.len..]
    if rest.ends_with('.c.v') {
        return rest[..rest.len - 4]
    }
    if rest.ends_with('.v') {
        return rest[..rest.len - 2]
    }
    return rest
}

// normalized_os supports normalized os handling for pref.
pub fn normalized_os(target_os string) string {
    return match target_os {
        'darwin' { 'macos' }
        'mac' { 'macos' }
        else { target_os }
    }
}

// normalized_target_os supports normalized target os handling for Preferences.
pub fn (p &Preferences) normalized_target_os() string {
    return normalized_os(p.target_os)
}

// is_cross_target reports whether is cross target applies in pref.
pub fn (p &Preferences) is_cross_target() bool {
    return p.normalized_target_os() != normalized_os(os.user_os())
}

// comptime_flag_value supports comptime flag value handling for pref.
pub fn comptime_flag_value(p &Preferences, name string) bool {
    match name {
        'macos', 'darwin', 'mac' {
            return p.normalized_target_os() == 'macos'
        }
        'linux' {
            return p.normalized_target_os() == 'linux'
        }
        'windows' {
            return p.normalized_target_os() == 'windows'
        }
        'freebsd' {
            return p.normalized_target_os() == 'freebsd'
        }
        'openbsd' {
            return p.normalized_target_os() == 'openbsd'
        }
        'netbsd' {
            return p.normalized_target_os() == 'netbsd'
        }
        'dragonfly' {
            return p.normalized_target_os() == 'dragonfly'
        }
        'android' {
            return p.normalized_target_os() == 'android'
        }
        'posix', 'unix' {
            return p.normalized_target_os() != 'windows'
        }
        'bsd' {
            tos := p.normalized_target_os()
            return tos == 'macos' || tos == 'freebsd' || tos == 'openbsd' || tos == 'netbsd'
                || tos == 'dragonfly'
        }
        'x64', 'amd64' {
            $if amd64 {
                return true
            }
            return false
        }
        'arm64', 'aarch64' {
            $if arm64 {
                return true
            }
            return false
        }
        'little_endian' {
            $if little_endian {
                return true
            }
            return false
        }
        'big_endian' {
            $if big_endian {
                return true
            }
            return false
        }
        'debug' {
            $if debug {
                return true
            }
            return false
        }
        'native' {
            return p.backend == 'arm64'
        }
        'builtin_write_buf_to_fd_should_use_c_write' {
            return p.backend == 'arm64'
        }
        'tinyc' {
            return p.backend == 'arm64'
        }
        'no_backtrace' {
            return p.backend == 'arm64' || name in p.user_defines
        }
        'gcboehm', 'gcboehm_opt', 'prealloc', 'autofree', 'no_bounds_checking', 'freestanding',
        'nofloat' {
            return name in p.user_defines
        }
        else {
            return name in p.user_defines
        }
    }
}

// comptime_optional_flag_value supports comptime optional flag value handling for pref.
pub fn comptime_optional_flag_value(p &Preferences, name string) bool {
    if name in p.user_defines {
        return true
    }
    return comptime_flag_value(p, name)
}

// comptime_pkgconfig_value supports comptime pkgconfig value handling for pref.
pub fn comptime_pkgconfig_value(name string) bool {
    result := os.execute('pkg-config --exists ${name}')
    return result.exit_code == 0
}