package paths

import (
	`context`
	`io/fs`
	`regexp`
	`sync`
	`time`

	`github.com/djherbis/times`
	`golang.org/x/sync/semaphore`
	`r00t2.io/goutils/bitmask`
)

// FsSearchCriteria contains filter criteria for SearchFsPaths* functions.
type FsSearchCriteria struct {
	// Root indicates the root to search.
	Root string `json:"root" toml:"RootPath" yaml:"Root Path" xml:"root,attr" validate:"dir"`
	// NoMatch, if true, will not return matches. If NoMatch and NoMismatch are both true, no results will be returned.
	NoMatch bool `json:"no_match" toml:"NoMatch" yaml:"No Matches" xml:"noMatch,attr"`
	// NoMismatch, if true, will not return mismatches. If NoMatch and NoMismatch are both true, no results will be returned.
	NoMismatch bool `json:"no_miss" toml:"NoMismatch" yaml:"No Mismatches" xml:"noMiss,attr"`
	/*
		TargetType defines what types of filesystem objects should be matched.
		It can consist of one or more (io/)fs.FileMode types OR'd together
		(ensure they are part of (io/)fs.ModeType).
		(You can use 0 to match regular files explicitly, and/or NoFiles = true to exclude them.)
	*/
	TargetType fs.FileMode `json:"type_tgt" toml:"TargetType" yaml:"Target Type" xml:"typeTgt,attr"`
	// NoFiles excludes files from TargetType-matching (as there isn't a way to explicitly exclude files otherwise if a non-zero mode is given).
	NoFiles bool `json:"no_file" toml:"ExcludeFiles" yaml:"Exclude Files" xml:"noFile,attr"`
	// FollowSymlinks, if true and a path being tested is a symlink, will use metadata (age, etc.) of the symlink itself rather than the link target.
	FollowSymlinks bool `json:"follow_sym" toml:"FollowSymlinks" yaml:"Follow Symlinks" xml:"followSym,attr"`
	// BasePtrn, if specified, will apply to the *base name (that is, quux.txt rather than /foo/bar/baz/quux.txt). See also PathPtrn.
	BasePtrn *regexp.Regexp `json:"ptrn_base,omitempty" toml:"BaseNamePattern,omitempty" yaml:"Base Name Pattern,omitempty" xml:"ptrnBase,attr,omitempty"`
	// PathPtrn, if specified, will apply to the *full path* (e.g. /foo/bar/baz/quux.txt, not just quux.txt). See also BasePtrn.
	PathPtrn *regexp.Regexp `json:"ptrn_path,omitempty" toml:"PathPattern,omitempty" yaml:"Path Pattern,omitempty" xml:"ptrnPath,attr,omitempty"`
	/*
		Age, if specified, indicates the comparison of Now againt the AgeType of filesystem objects.
		Use OlderThan to indicate if it should be older or newer.
	*/
	Age *time.Duration `json:"age,omitempty" toml:"Age,omitempty" yaml:"Age,omitempty" xml:"age,attr,omitempty"`
	/*
		AgeType can be one (or more, OR'd together) of the Time* constants in this package (TimeAny, TimeAccessed, TimeCreated,
		TimeChanged, TimeModified) to indicate what timestamp(s) to use for comparing Age.

		The zero-value is TimeAny.

		The first matching timestamp will pass all time comparisons.
		Be mindful of timestamp type support/limitations per OS/filesystem of Root.

		Completely unused if Age is nil.
	*/
	AgeType pathTimeType `json:"type_age" toml:"AgeType" yaml:"Age Type" xml:"typeAge,attr"`
	/*
		OlderThan, if true (and Age is not nil), indicates that matching filesystem objects should have their
		AgeType older than Now. If false, their AgeType should be *newer* than Now.

		Completely unused if Age is nil.
	*/
	OlderThan bool `json:"older" toml:"OlderThan" yaml:"Older Than" xml:"older,attr"`
	/*
		Now expresses a time to compare to Age via AgeType and OlderThan.
		Note that it may be any valid time, not necessarily "now".
		If Age is specified but Now is nil, it will be populated with time.Now() when the search is invoked.

		Completely unused if Age is nil.
	*/
	Now *time.Time `json:"now,omitempty" toml:"Now,omitempty" yaml:"Now,omitempty" xml:"now,attr,omitempty"`
}

// FsSearchCriteriaAsync extends FsSearchCriteria for use in an asynchronous (goroutine) manner.
type FsSearchCriteriaAsync struct {
	FsSearchCriteria
	/*
		WG should be a non-nil pointer to a sync.WaitGroup.
		This is used to manage searching completion to the caller.

		.Done() will be called once within the search function, but no .Add() will be called;
		.Add() should be done by the caller beforehand.
	*/
	WG *sync.WaitGroup
	// ResChan must be a non-nil channel for (positive) match results to be sent to.
	ResChan chan *FsSearchResult
	// MismatchChan, if not nil, will have negative matches/"misses" sent to it.
	MismatchChan chan *FsSearchResult
	/*
		ErrChan should be a non-nil error channel for any unexpected errors encountered.

		If nil, a panic will be raised.
	*/
	ErrChan chan error
	/*
		Semaphore is completely optional, but if non-nil
		it will be used to limit concurrent filesystem
		object processing.

		It is generally a Very Good Idea(TM) to use this,
		as the default is to dispatch all processing concurrently.
		This can lead to some heavy I/O and CPU wait.

		(See https://pkg.go.dev/golang.org/x/sync/semaphore for details.)
	*/
	Semaphore *semaphore.Weighted
	/*
		SemaphoreCtx is the context.Context to use for Semaphore.
		If nil (but Sempaphore is not), one will be created locally/internally.
	*/
	SemaphoreCtx context.Context
}

// FsSearchResult contains a match/miss result for FsSearchCriteria and FsSearchCriteriaAsync.
type FsSearchResult struct {
	/*
		Path is the path to the object on the filesystem.
		It may or may not exist at the time of return,
		but will not be an empty string.
	*/
	Path string `json:"path" toml:"Path" yaml:"Path" xml:"path,attr"`
	// DirEntry is the fs.DirEntry for the Path; note that .Name() is the base name only. TODO: serialization?
	DirEntry fs.DirEntry `json:"-" toml:"-" yaml:"-" xml:"-"`
	// FileInfo is the fs.FileInfo for the Path; note that .Name() is the base name only. TODO: serialization?
	FileInfo fs.FileInfo `json:"-" toml:"-" yaml:"-" xml:"-"`
	// Criteria is the evaluated criteria specified that this FsSearchResult matched.
	Criteria *FsSearchCriteria `json:"criteria" toml:"Criteria" yaml:"Criteria" xml:"criteria"`
	// Times holds the mtime, ctime, etc. of the filesystem object (where supported). TODO: serialization?
	Times times.Timespec `json:"-" toml:"-" yaml:"-" xml:"-"`
	// MissReason contains the reason the result is a miss (MissNoMiss if a match); see the Miss* constants.
	MissReason missReason `json:"miss_reason" toml:"MissReason" yaml:"Miss Reason" xml:"miss,attr"`
}

type missReason string

type pathMode bitmask.MaskBit

type pathTimeType bitmask.MaskBit