package cli

import (
	"flag"
	"fmt"
	"io"
	"io/fs"
	"os"
	"path/filepath"
	"sort"

	"git.vakhrushev.me/av/convy/internal/check"
	"git.vakhrushev.me/av/convy/internal/doc"
	"git.vakhrushev.me/av/convy/internal/manifest"
	"git.vakhrushev.me/av/convy/internal/project"
)

// convy check stays at the top level and reaches for no suite. The form of a
// rule is one and the same, the local rules of the repository on X prefixes are
// written by that same form, and checking what lies here has to work without a
// network and without knowing where the copies came from.

func runCheck(env Env, args []string) ExitCode {
	fs := flag.NewFlagSet("convy check", flag.ContinueOnError)
	fs.SetOutput(env.Err)
	root := fs.String("root", "", "root of the project; it is looked up upwards by default")
	forComponent := fs.String("for", "", "component to check; every one of them by default")
	quiet := fs.Bool("quiet", false, "print findings only")
	if err := fs.Parse(args); err != nil {
		return Usage
	}

	dir, code := projectRoot(env, *root)
	if code != OK {
		return code
	}
	m, err := manifest.LoadProject(dir)
	if err != nil {
		fmt.Fprintln(env.Err, err)
		return Usage
	}
	names, code := components(env, m, *forComponent)
	if code != OK {
		return code
	}

	var docs []*doc.Document
	var broken []error
	for _, name := range names {
		found, errs := copies(dir, m.Components[name].Dir)
		docs = append(docs, found...)
		broken = append(broken, errs...)
	}

	rep := check.Copies(docs)
	for _, err := range broken {
		fmt.Fprintf(env.Err, "%s\n", err)
	}
	printCopyReport(env.Out, rep, len(docs), len(names), *quiet)
	if rep.Errors() > 0 || len(broken) > 0 {
		return Failed
	}
	return OK
}

// copies collects the assembled conventions of one component directory.
//
// What is a copy is decided by the origin key rather than by the name of the
// file: README.md belongs to the repository, READING.md belongs to the suite,
// and a file whose origin key was taken away has become a document of the
// repository — none of the three answers to the form of a rule.
func copies(root, dir string) ([]*doc.Document, []error) {
	var docs []*doc.Document
	var broken []error
	base := filepath.Join(root, filepath.FromSlash(dir))

	err := filepath.WalkDir(base, func(name string, entry fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if entry.IsDir() || filepath.Ext(entry.Name()) != ".md" {
			return nil
		}
		rel, err := filepath.Rel(root, name)
		if err != nil {
			return err
		}
		rel = filepath.ToSlash(rel)
		d, err := doc.Load(rel, name)
		if err != nil {
			broken = append(broken, err)
			return nil
		}
		if d.Front.Origin == "" {
			return nil
		}
		docs = append(docs, d)
		return nil
	})
	if err != nil && !os.IsNotExist(err) {
		broken = append(broken, fmt.Errorf("walking %s: %w", dir, err))
	}
	sort.Slice(docs, func(i, j int) bool { return docs[i].Path < docs[j].Path })
	return docs, broken
}

func printCopyReport(w io.Writer, rep *check.Report, files, comps int, quiet bool) {
	findings := rep.Findings()
	current := ""
	for _, f := range findings {
		if f.Path != current {
			if current != "" {
				fmt.Fprintln(w)
			}
			fmt.Fprintf(w, "%s\n", f.Path)
			current = f.Path
		}
		where := ""
		if f.Line > 0 {
			where = fmt.Sprintf(":%d", f.Line)
		}
		fmt.Fprintf(w, "  %s%s  %s [%s]\n", f.Severity, where, f.Msg, f.Family)
	}

	if quiet {
		return
	}
	if len(findings) > 0 {
		fmt.Fprintln(w)
	}
	fmt.Fprintf(w, "project: %s in %s\n", plural(files, "file"), plural(comps, "component"))
	switch {
	case rep.Errors() > 0:
		fmt.Fprintf(w, "errors: %d, warnings: %d\n", rep.Errors(), rep.Warnings())
	case rep.Warnings() > 0:
		fmt.Fprintf(w, "no errors, warnings: %d\n", rep.Warnings())
	case files == 0:
		fmt.Fprintf(w, "nothing to check: no file carries an origin key; convy pull assembles the copies\n")
	default:
		fmt.Fprintf(w, "the copies hold the form; everything below %s is the repository's own\n", project.LocalMarker)
	}
}