// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package confyg

import (
	"bytes"
	"errors"
	"fmt"
	"sort"
	"strconv"
	"strings"
)

type File struct {
	Syntax *FileSyntax
}

func Parse(file string, data []byte) (*File, error) {
	fs, err := parse(file, data)
	if err != nil {
		return nil, err
	}
	f := &File{
		Syntax: fs,
	}

	var errs bytes.Buffer
	for _, x := range fs.Stmt {
		switch x := x.(type) {
		case *Line:
			f.add(&errs, x, x.Token[0], x.Token[1:])

		case *LineBlock:
			if len(x.Token) > 1 {
				fmt.Fprintf(&errs, "%s:%d: unknown block type: %s\n", file, x.Start.Line, strings.Join(x.Token, " "))
				continue
			}
			switch x.Token[0] {
			default:
				fmt.Fprintf(&errs, "%s:%d: unknown block type: %s\n", file, x.Start.Line, strings.Join(x.Token, " "))
				continue
			case "module", "require", "exclude", "replace":
				for _, l := range x.Line {
					f.add(&errs, l, x.Token[0], l.Token)
				}
			}
		}
	}

	if errs.Len() > 0 {
		return nil, errors.New(strings.TrimRight(errs.String(), "\n"))
	}
	return f, nil
}

func (f *File) add(errs *bytes.Buffer, line *Line, verb string, args []string) {
	// TODO: We should pass in a flag saying whether this module is a dependency.
	// If so, we should ignore all unknown directives and not attempt to parse
	// replace and exclude either. They don't matter, and it will work better for
	// forward compatibility if we can depend on modules that have local changes.

	// TODO: For the target module (not dependencies), maybe we should
	// relax the semver requirement and rewrite the file with updated info
	// after resolving any versions. That would let people type commit hashes
	// or tags or branch names, and then vgo would fix them.

	switch verb {
	default:
		fmt.Fprintf(errs, "%s:%d: unknown directive: %s\n", f.Syntax.Name, line.Start.Line, verb)
	}
}

func isDirectoryPath(ns string) bool {
	// Because go.mod files can move from one system to another,
	// we check all known path syntaxes, both Unix and Windows.
	return strings.HasPrefix(ns, "./") || strings.HasPrefix(ns, "../") || strings.HasPrefix(ns, "/") ||
		strings.HasPrefix(ns, `.\`) || strings.HasPrefix(ns, `..\`) || strings.HasPrefix(ns, `\`) ||
		len(ns) >= 2 && ('A' <= ns[0] && ns[0] <= 'Z' || 'a' <= ns[0] && ns[0] <= 'z') && ns[1] == ':'
}

func isString(s string) bool {
	return s != "" && s[0] == '"'
}

func parseString(s *string) (string, error) {
	t, err := strconv.Unquote(*s)
	if err != nil {
		return "", err
	}
	*s = strconv.Quote(t)
	return t, nil
}

func (f *File) Format() ([]byte, error) {
	return Format(f.Syntax), nil
}

func (f *File) SortBlocks() {
	for _, stmt := range f.Syntax.Stmt {
		block, ok := stmt.(*LineBlock)
		if !ok {
			continue
		}
		sort.Slice(block.Line, func(i, j int) bool {
			li := block.Line[i]
			lj := block.Line[j]
			for k := 0; k < len(li.Token) && k < len(lj.Token); k++ {
				if li.Token[k] != lj.Token[k] {
					return li.Token[k] < lj.Token[k]
				}
			}
			return len(li.Token) < len(lj.Token)
		})
	}
}