package main

import (
	"context"
	"errors"
	"fmt"
	"net/url"
	"os"
	"os/signal"
	"path/filepath"
	"syscall"
	"time"

	"github.com/grmrgecko/repo-sync/mirror"
)

// SyncArgs holds the flags and positional arguments shared by every
// repository type.
type SyncArgs struct {
	Trim     int  `help:"Number of leading URL path components to drop when building the destination path." default:"0"`
	Flat     bool `help:"Place repositories directly in the destination directory without copying the URL path."`
	Discover bool `help:"Treat each URL as a directory index and crawl it for repositories."`
	Depth    int  `help:"Maximum directory depth crawled in discovery mode." default:"5"`
	Workers  int  `help:"Number of concurrent download workers." default:"4"`
	Verify   bool `help:"Re-verify checksums of files that already exist locally."`
	Prune    bool `help:"Delete local files that are no longer part of the repository."`

	PruneGrace time.Duration `help:"Keep files that left the repository for this long before pruning them (e.g. 72h)."`
	DryRun     bool          `help:"Report what would be downloaded or pruned without changing the repository."`

	Args []string `arg:"" name:"url" help:"Repository or mirrorlist URLs followed by the destination directory."`
}

// options validates the shared arguments and builds the mirror options.
func (s *SyncArgs) options(typ mirror.RepoType) (*mirror.Options, error) {
	if len(s.Args) < 2 {
		return nil, errors.New("expected at least one repository URL and a destination directory")
	}
	urls := s.Args[:len(s.Args)-1]
	for _, raw := range urls {
		u, err := url.Parse(raw)
		if err != nil || (u.Scheme != "http" && u.Scheme != "https") || u.Host == "" {
			return nil, fmt.Errorf("invalid repository URL %q", raw)
		}
	}
	dest, err := filepath.Abs(s.Args[len(s.Args)-1])
	if err != nil {
		return nil, err
	}
	if s.Trim < 0 {
		return nil, errors.New("trim must not be negative")
	}
	if s.Depth < 0 {
		return nil, errors.New("depth must not be negative")
	}
	if s.PruneGrace < 0 {
		return nil, errors.New("prune grace must not be negative")
	}
	return &mirror.Options{
		Type:          typ,
		URLs:          urls,
		Destination:   dest,
		Trim:          s.Trim,
		Flat:          s.Flat,
		Discover:      s.Discover,
		DiscoverDepth: s.Depth,
		Workers:       s.Workers,
		Verify:        s.Verify,
		Prune:         s.Prune,
		PruneGrace:    s.PruneGrace,
		DryRun:        s.DryRun,
	}, nil
}

// run executes a synchronization with signal-aware cancellation.
func (s *SyncArgs) run(opts *mirror.Options) error {
	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()
	return mirror.Sync(ctx, opts)
}

// RPMCmd synchronizes RPM repositories.
type RPMCmd struct {
	SyncArgs `embed:""`
}

// Run performs the RPM synchronization.
func (c *RPMCmd) Run() error {
	opts, err := c.options(mirror.RepoRPM)
	if err != nil {
		return err
	}
	return c.run(opts)
}

// ArchCmd synchronizes Arch Linux repositories.
type ArchCmd struct {
	SyncArgs `embed:""`
}

// Run performs the Arch Linux synchronization.
func (c *ArchCmd) Run() error {
	opts, err := c.options(mirror.RepoArch)
	if err != nil {
		return err
	}
	return c.run(opts)
}

// ApkCmd synchronizes Alpine Linux repositories.
type ApkCmd struct {
	SyncArgs `embed:""`
}

// Run performs the Alpine Linux synchronization.
func (c *ApkCmd) Run() error {
	opts, err := c.options(mirror.RepoApk)
	if err != nil {
		return err
	}
	return c.run(opts)
}

// DebCmd synchronizes DEB repositories.
type DebCmd struct {
	Component []string `help:"Limit synchronization to these components."`
	Arch      []string `help:"Limit synchronization to these architectures; include \"source\" to keep source indexes."`

	SyncArgs `embed:""`
}

// Run performs the DEB synchronization.
func (c *DebCmd) Run() error {
	opts, err := c.options(mirror.RepoDeb)
	if err != nil {
		return err
	}
	opts.Components = c.Component
	opts.Architectures = c.Arch
	return c.run(opts)
}