package dockeroptions

import (
	"fmt"
	"slices"
	"sort"
	"strings"

	"github.com/dokku/dokku/plugins/common"
	"mvdan.cc/sh/v3/syntax"
)

// DefaultProcessType is the sentinel process-type key used for options that
// apply to every container in an app (i.e. options not scoped to a specific
// Procfile process type).
const DefaultProcessType = "_default_"

// SplitOptionString shell-tokenizes input, groups tokens on flag boundaries,
// and returns one re-serialized option per group. Tokenization honors quotes
// for word boundaries but performs no expansion, so parameter expansions,
// command substitutions, and other shell metacharacters are stored verbatim
// and passed through to the container as written (the bash scheduler splits
// them the same way, without expansion). A docker-options subcommand flag
// (currently just --process) that lands inside the option content - because
// the user typed it after the app name, where pflag's SetInterspersed(false)
// hands it back as positional - is lifted into the returned processes slice
// rather than stored as a docker option. The caller merges those processes
// with whatever pflag already captured. Empty or whitespace-only input returns
// empty slices.
func SplitOptionString(input string) (options []string, processes []string, err error) {
	if strings.TrimSpace(input) == "" {
		return nil, nil, nil
	}

	fields, err := literalFields(input)
	if err != nil {
		return nil, nil, fmt.Errorf("Unable to parse docker option: %s", err.Error())
	}

	for _, group := range groupOptionTokens(fields) {
		head := group[0]
		if head == "--process" {
			if len(group) < 2 {
				return nil, nil, fmt.Errorf("--process requires a value")
			}
			if len(group) > 2 {
				return nil, nil, fmt.Errorf("--process accepts a single value, got %d", len(group)-1)
			}
			processes = append(processes, group[1])
			continue
		}
		if strings.HasPrefix(head, "--process=") {
			if len(group) > 1 {
				return nil, nil, fmt.Errorf("--process=value cannot be followed by additional tokens")
			}
			processes = append(processes, head[len("--process="):])
			continue
		}
		options = append(options, joinShellTokens(group))
	}

	return options, processes, nil
}

// groupOptionTokens groups shell words on flag boundaries so each group holds
// one flag and the values that follow it. A group is emitted for every token
// that looks like a flag, meaning `--build-arg X=Y --link a` yields
// [["--build-arg" "X=Y"] ["--link" "a"]]. Tokens preceding the first flag stay
// in the leading group so malformed input is never silently dropped.
func groupOptionTokens(fields []string) [][]string {
	var groups [][]string
	var current []string
	for _, tok := range fields {
		if isFlagToken(tok) && len(current) > 0 {
			groups = append(groups, current)
			current = nil
		}
		current = append(current, tok)
	}
	if len(current) > 0 {
		groups = append(groups, current)
	}
	return groups
}

// canonicalOptionsFromLine re-serializes a stored option line into the
// canonical, shell-quoted form `docker-options:add` produces, splitting it on
// flag boundaries so a line carrying several flags becomes one entry per flag.
// Unlike SplitOptionString it never lifts `--process`: a stored line is data
// rather than command-line input.
//
// The line is returned unchanged when it cannot be parsed, or when the parser
// stops before consuming all of it - a line whose tail begins with an unquoted
// `#` reads as a shell comment, and dropping it would lose stored data.
func canonicalOptionsFromLine(line string) []string {
	fields, end, err := literalFieldsWithEnd(line)
	if err != nil || end < len(strings.TrimRight(line, " \t")) {
		return []string{line}
	}

	groups := groupOptionTokens(fields)
	options := make([]string, 0, len(groups))
	for _, group := range groups {
		options = append(options, joinShellTokens(group))
	}
	return options
}

// optionsEqual reports whether two option strings denote the same docker
// option. Exact equality short-circuits; otherwise both sides are
// shell-tokenized without expansion and compared word by word, so an option
// held in a non-canonical form - drained verbatim out of a pre-0.38.25
// DOCKER_OPTIONS_<PHASE> file, or written directly by another plugin - still
// matches the canonically re-serialized string the CLI builds. Input that
// cannot be parsed never matches.
func optionsEqual(stored string, option string) bool {
	if stored == option {
		return true
	}

	storedFields, err := literalFields(stored)
	if err != nil {
		return false
	}

	optionFields, err := literalFields(option)
	if err != nil {
		return false
	}

	return slices.Equal(storedFields, optionFields)
}

// literalFields splits input into shell words using the parser directly, so
// quotes delimit words and are stripped from the stored value, but nothing is
// expanded. Parameter expansions, command substitutions, and other
// metacharacters are preserved verbatim. Malformed input, such as an unbalanced
// quote, returns the parser error.
func literalFields(input string) ([]string, error) {
	fields, _, err := literalFieldsWithEnd(input)
	return fields, err
}

// literalFieldsWithEnd is literalFields plus the byte offset just past the last
// word the parser consumed. Callers that must not lose data compare the offset
// against the length of the input to detect a tail the parser skipped, such as
// a shell comment.
func literalFieldsWithEnd(input string) ([]string, int, error) {
	parser := syntax.NewParser()
	var fields []string
	end := 0
	for word, err := range parser.WordsSeq(strings.NewReader(input)) {
		if err != nil {
			return nil, 0, err
		}
		fields = append(fields, literalWordValue(input, word.Parts))
		end = int(word.End().Offset())
	}
	return fields, end, nil
}

// literalWordValue reconstructs the unquoted, unexpanded value of a shell word.
// Literal and single-quoted parts contribute their literal text; double-quoted
// parts have their surrounding quotes dropped while their contents stay
// literal; every other part - parameter expansions, command substitutions,
// arithmetic expansions - contributes its original source text unchanged.
// Backslash escapes are removed the same way the shell removes them during
// quote removal so a value such as `Host(\`app\`)` round-trips to `Host(`app`)`.
func literalWordValue(input string, parts []syntax.WordPart) string {
	var sb strings.Builder
	for _, part := range parts {
		switch p := part.(type) {
		case *syntax.Lit:
			sb.WriteString(unquoteBackslashes(p.Value, false))
		case *syntax.SglQuoted:
			sb.WriteString(p.Value)
		case *syntax.DblQuoted:
			for _, inner := range p.Parts {
				if lit, ok := inner.(*syntax.Lit); ok {
					sb.WriteString(unquoteBackslashes(lit.Value, true))
					continue
				}
				sb.WriteString(input[inner.Pos().Offset():inner.End().Offset()])
			}
		default:
			sb.WriteString(input[part.Pos().Offset():part.End().Offset()])
		}
	}
	return sb.String()
}

// unquoteBackslashes removes backslashes the way the shell does during quote
// removal. Inside double quotes only \$, \`, \", \\, and an escaped newline
// lose their backslash; unquoted, a backslash escapes any following character.
func unquoteBackslashes(s string, inDblQuotes bool) string {
	if !strings.Contains(s, "\\") {
		return s
	}
	var sb strings.Builder
	for i := 0; i < len(s); i++ {
		if s[i] == '\\' && i+1 < len(s) {
			next := s[i+1]
			if next == '\n' {
				i++
				continue
			}
			if !inDblQuotes || next == '$' || next == '`' || next == '"' || next == '\\' {
				sb.WriteByte(next)
				i++
				continue
			}
		}
		sb.WriteByte(s[i])
	}
	return sb.String()
}

// isFlagToken reports whether tok looks like a CLI flag (long or short) rather
// than a value. Treating any token that begins with `-` and has more than one
// character as a flag matches docker's flag conventions and avoids the need
// for a per-flag whitelist.
func isFlagToken(tok string) bool {
	return len(tok) > 1 && tok[0] == '-'
}

// joinShellTokens joins tokens into a single string suitable for storage,
// shell-quoting any token that contains characters the bash scheduler's
// `eval` re-tokenization would interpret. The stored line round-trips through
// `eval set -- "$line"` back to the original token slice.
func joinShellTokens(tokens []string) string {
	parts := make([]string, len(tokens))
	for i, tok := range tokens {
		parts[i] = quoteShellArg(tok)
	}
	return strings.Join(parts, " ")
}

// quoteShellArg returns s wrapped in single quotes when it contains characters
// the shell would otherwise interpret (whitespace, quotes, expansion sigils,
// globs, redirections, etc.). Embedded single quotes are escaped with the
// standard `'\''` close-escape-open sequence. Tokens free of such characters
// are returned verbatim so the stored representation stays human-readable for
// the common case.
func quoteShellArg(s string) string {
	if s == "" {
		return "''"
	}
	if !needsShellQuoting(s) {
		return s
	}
	return "'" + strings.ReplaceAll(s, "'", `'\''`) + "'"
}

func needsShellQuoting(s string) bool {
	for _, r := range s {
		switch r {
		case ' ', '\t', '\n', '"', '\'', '$', '`', '\\',
			'*', '?', '[', ']', '<', '>', '|', '&', ';',
			'(', ')', '{', '}', '!', '#', '~':
			return true
		}
	}
	return false
}

func propertyKey(processType, phase string) string {
	if processType == "" {
		processType = DefaultProcessType
	}
	return fmt.Sprintf("%s.%s", processType, phase)
}

// SetDockerOptionForPhases sets a `--name=value` option in the default scope
// for the specified phases, replacing any existing entry with the same name.
func SetDockerOptionForPhases(appName string, phases []string, name string, value string) error {
	return SetDockerOptionForProcessPhases(appName, []string{DefaultProcessType}, phases, name, value)
}

// SetDockerOptionForProcessPhases sets a `--name=value` option for the specified
// process types and phases, replacing any existing entry with the same name.
func SetDockerOptionForProcessPhases(appName string, processTypes []string, phases []string, name string, value string) error {
	if len(processTypes) == 0 {
		processTypes = []string{DefaultProcessType}
	}
	for _, processType := range processTypes {
		for _, phase := range phases {
			options, err := GetDockerOptionsForProcessPhase(appName, processType, phase)
			if err != nil {
				return err
			}

			newOptions := []string{}
			for _, option := range options {
				if strings.HasPrefix(option, fmt.Sprintf("--%s=", name)) {
					continue
				}
				newOptions = append(newOptions, option)
			}

			newOptions = append(newOptions, fmt.Sprintf("--%s=%s", name, value))
			sort.Strings(newOptions)
			if err := writeDockerOptionsForProcessPhase(appName, processType, phase, newOptions); err != nil {
				return err
			}
		}
	}
	return nil
}

// AddDockerOptionToPhases adds an option to the default scope for the specified phases.
func AddDockerOptionToPhases(appName string, phases []string, option string) error {
	return AddDockerOptionToProcessPhases(appName, []string{DefaultProcessType}, phases, option)
}

// AddDockerOptionToProcessPhases adds an option to the specified process types and phases.
func AddDockerOptionToProcessPhases(appName string, processTypes []string, phases []string, option string) error {
	if len(processTypes) == 0 {
		processTypes = []string{DefaultProcessType}
	}
	for _, processType := range processTypes {
		for _, phase := range phases {
			options, err := GetDockerOptionsForProcessPhase(appName, processType, phase)
			if err != nil {
				return err
			}

			options = append(options, option)
			sort.Strings(options)
			if err := writeDockerOptionsForProcessPhase(appName, processType, phase, options); err != nil {
				return err
			}
		}
	}
	return nil
}

// GetDockerOptionsForPhase returns the docker options stored under the default
// scope for the specified phase.
func GetDockerOptionsForPhase(appName string, phase string) ([]string, error) {
	return GetDockerOptionsForProcessPhase(appName, DefaultProcessType, phase)
}

// GetDockerOptionsForProcessPhase returns the docker options stored under the
// given process-type scope for the specified phase. An empty processType is
// treated as the default scope.
func GetDockerOptionsForProcessPhase(appName, processType, phase string) ([]string, error) {
	options, err := common.PropertyListGet("docker-options", appName, propertyKey(processType, phase))
	if err != nil {
		return nil, fmt.Errorf("Unable to read docker options for %s.%s.%s: %s", appName, processType, phase, err.Error())
	}

	trimmed := make([]string, 0, len(options))
	for _, option := range options {
		option = strings.TrimSpace(option)
		if option == "" {
			continue
		}
		trimmed = append(trimmed, option)
	}
	return trimmed, nil
}

// RemoveDockerOptionFromPhases removes an option from the default scope for the specified phases.
func RemoveDockerOptionFromPhases(appName string, phases []string, option string) error {
	return RemoveDockerOptionFromProcessPhases(appName, []string{DefaultProcessType}, phases, option)
}

// RemoveDockerOptionFromProcessPhases removes an option from the specified
// process types and phases. Stored options are matched against the requested
// option by shell word rather than by raw string, so an entry held in a
// non-canonical form still matches the canonically re-serialized string the
// CLI hands down.
func RemoveDockerOptionFromProcessPhases(appName string, processTypes []string, phases []string, option string) error {
	if len(processTypes) == 0 {
		processTypes = []string{DefaultProcessType}
	}
	for _, processType := range processTypes {
		for _, phase := range phases {
			options, err := GetDockerOptionsForProcessPhase(appName, processType, phase)
			if err != nil {
				return err
			}

			newOptions := []string{}
			for _, opt := range options {
				if !optionsEqual(opt, option) {
					newOptions = append(newOptions, opt)
				}
			}

			sort.Strings(newOptions)
			if err := writeDockerOptionsForProcessPhase(appName, processType, phase, newOptions); err != nil {
				return err
			}
		}
	}
	return nil
}

// GetSpecifiedDockerOptionsForPhase returns the docker options for the specified
// phase (default scope) that are in the desiredOptions list. It expects
// desiredOptions entries in the form "--option" and matches against options
// stored as "--option", "--option=value", or "--option value".
func GetSpecifiedDockerOptionsForPhase(appName string, phase string, desiredOptions []string) (map[string][]string, error) {
	foundOptions := map[string][]string{}
	options, err := GetDockerOptionsForPhase(appName, phase)
	if err != nil {
		return foundOptions, err
	}

	for _, option := range options {
		for _, desiredOption := range desiredOptions {
			if option == desiredOption {
				foundOptions[desiredOption] = []string{}
				break
			}

			if strings.HasPrefix(option, fmt.Sprintf("%s=", desiredOption)) {
				if _, ok := foundOptions[desiredOption]; !ok {
					foundOptions[desiredOption] = []string{}
				}

				parts := strings.SplitN(option, "=", 2)
				if len(parts) != 2 {
					common.LogWarn(fmt.Sprintf("Invalid docker option found for %s: %s", appName, option))
					continue
				}

				foundOptions[desiredOption] = append(foundOptions[desiredOption], parts[1])
				break
			}

			if strings.HasPrefix(option, fmt.Sprintf("%s ", desiredOption)) {
				if _, ok := foundOptions[desiredOption]; !ok {
					foundOptions[desiredOption] = []string{}
				}

				parts := strings.SplitN(option, " ", 2)
				if len(parts) != 2 {
					common.LogWarn(fmt.Sprintf("Invalid docker option found for %s: %s", appName, option))
					continue
				}

				foundOptions[desiredOption] = append(foundOptions[desiredOption], parts[1])
				break
			}
		}
	}

	return foundOptions, nil
}

// ListProcessTypesWithOptions returns the sorted list of process types that
// have at least one option configured, excluding DefaultProcessType.
func ListProcessTypesWithOptions(appName string) ([]string, error) {
	properties, err := common.PropertyGetAll("docker-options", appName)
	if err != nil {
		return nil, err
	}

	seen := map[string]bool{}
	for key := range properties {
		processType, _, ok := splitPropertyKey(key)
		if !ok {
			continue
		}
		if processType == DefaultProcessType {
			continue
		}
		seen[processType] = true
	}

	processTypes := make([]string, 0, len(seen))
	for processType := range seen {
		processTypes = append(processTypes, processType)
	}
	sort.Strings(processTypes)
	return processTypes, nil
}

func splitPropertyKey(key string) (processType, phase string, ok bool) {
	idx := strings.LastIndex(key, ".")
	if idx <= 0 || idx == len(key)-1 {
		return "", "", false
	}
	processType = key[:idx]
	phase = key[idx+1:]
	if !isValidPhase(phase) {
		return "", "", false
	}
	return processType, phase, true
}

func writeDockerOptionsForProcessPhase(appName, processType, phase string, options []string) error {
	return common.PropertyListWrite("docker-options", appName, propertyKey(processType, phase), options)
}