/*
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements.  See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
the License.  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package tasks

import (
	"fmt"
	"gorm.io/gorm"
	"regexp"
	"sort"
	"strings"
	"time"

	"github.com/apache/incubator-devlake/models/domainlayer/code"
	"github.com/apache/incubator-devlake/plugins/core/dal"
)

type RefdiffOptions struct {
	RepoId string
	Tasks  []string `json:"tasks,omitempty"`
	Pairs  []RefPair

	TagsPattern string // The Pattern to match from all tags
	TagsLimit   int    // How many tags be matched should be used.
	TagsOrder   string // The Rule to Order the tag list

	AllPairs RefCommitPairs // Pairs and TagsPattern Pairs
}

type RefdiffTaskData struct {
	Options *RefdiffOptions
	Since   *time.Time
}

type RefPair struct {
	NewRef string
	OldRef string
}
type RefCommitPair [4]string
type RefPairList [2]string
type RefCommitPairs []RefCommitPair
type RefPairLists []RefPairList

type Refs []code.Ref
type RefsAlphabetically Refs
type RefsReverseAlphabetically Refs
type RefsSemver Refs
type RefsReverseSemver Refs

func (rs Refs) Len() int {
	return len(rs)
}

func (rs RefsAlphabetically) Len() int {
	return len(rs)
}

func (rs RefsAlphabetically) Less(i, j int) bool {
	return rs[i].Id < rs[j].Id
}

func (rs RefsAlphabetically) Swap(i, j int) {
	rs[i], rs[j] = rs[j], rs[i]
}

func (rs RefsReverseAlphabetically) Len() int {
	return len(rs)
}

func (rs RefsReverseAlphabetically) Less(i, j int) bool {
	return rs[i].Id > rs[j].Id
}

func (rs RefsReverseAlphabetically) Swap(i, j int) {
	rs[i], rs[j] = rs[j], rs[i]
}

func (rs RefsSemver) Len() int {
	return len(rs)
}

func (rs RefsSemver) Less(i, j int) bool {
	parti := strings.Split(rs[i].Name, ".")
	partj := strings.Split(rs[j].Name, ".")

	for k := 0; k < len(partj); k++ {
		if k >= len(parti) {
			return true
		}

		if len(parti[k]) < len(partj[k]) {
			return true
		}
		if len(parti[k]) > len(partj[k]) {
			return false
		}

		if parti[k] < partj[k] {
			return true
		}
		if parti[k] > partj[k] {
			return false
		}
	}
	return false
}

func (rs RefsSemver) Swap(i, j int) {
	rs[i], rs[j] = rs[j], rs[i]
}

func (rs RefsReverseSemver) Len() int {
	return len(rs)
}

func (rs RefsReverseSemver) Less(i, j int) bool {
	return RefsSemver(rs).Less(j, i)
}

func (rs RefsReverseSemver) Swap(i, j int) {
	rs[i], rs[j] = rs[j], rs[i]
}

// CaculateTagPattern Calculate the TagPattern order by tagsOrder and return the Refs
func CaculateTagPattern(db dal.Dal, tagsPattern string, tagsLimit int, tagsOrder string) (Refs, error) {
	rs := Refs{}

	// caculate Pattern part
	if tagsPattern == "" || tagsLimit <= 1 {
		return rs, nil
	}
	rows, err := db.Cursor(
		dal.From("refs"),
		dal.Where(""),
		dal.Orderby("created_date desc"),
	)

	if err != nil {
		return rs, err
	}
	defer rows.Next()
	r, err := regexp.Compile(tagsPattern)
	if err != nil {
		return rs, fmt.Errorf("unable to parse: %s\r\n%s", tagsPattern, err.Error())
	}
	for rows.Next() {
		var ref code.Ref
		err = db.Fetch(rows, &ref)
		if err != nil {
			return rs, err
		}

		if ok := r.Match([]byte(ref.Name)); ok {
			rs = append(rs, ref)
		}
	}
	switch tagsOrder {
	case "alphabetically":
		sort.Sort(RefsAlphabetically(rs))
	case "reverse alphabetically":
		sort.Sort(RefsReverseAlphabetically(rs))
	case "semver":
		sort.Sort(RefsSemver(rs))
	case "reverse semver":
		sort.Sort(RefsReverseSemver(rs))
	default:
	}

	if tagsLimit < rs.Len() {
		rs = rs[:tagsLimit]
	}

	return rs, nil
}

// CalculateCommitPairs Calculate the commits pairs both from Options.Pairs and TagPattern
func CalculateCommitPairs(db dal.Dal, repoId string, pairs []RefPair, rs Refs) (RefCommitPairs, error) {
	commitPairs := make(RefCommitPairs, 0, len(rs)+len(pairs))
	for i := 1; i < len(rs); i++ {
		commitPairs = append(commitPairs, [4]string{rs[i-1].CommitSha, rs[i].CommitSha, rs[i-1].Name, rs[i].Name})
	}

	// caculate pairs part
	// convert ref pairs into commit pairs
	ref2sha := func(refName string) (string, error) {
		ref := &code.Ref{}
		if refName == "" {
			return "", fmt.Errorf("ref name is empty")
		}
		ref.Id = fmt.Sprintf("%s:%s", repoId, refName)
		err := db.First(ref)
		if err != nil && err != gorm.ErrRecordNotFound {
			return "", fmt.Errorf("faild to load Ref info for repoId:%s, refName:%s", repoId, refName)
		}
		return ref.CommitSha, nil
	}

	for i, refPair := range pairs {
		// get new ref's commit sha
		newCommit, err := ref2sha(refPair.NewRef)
		if err != nil {
			return RefCommitPairs{}, fmt.Errorf("failed to load commit sha for NewRef on pair #%d: %w", i, err)
		}
		// get old ref's commit sha
		oldCommit, err := ref2sha(refPair.OldRef)
		if err != nil {
			return RefCommitPairs{}, fmt.Errorf("failed to load commit sha for OleRef on pair #%d: %w", i, err)
		}

		have := false
		for _, cp := range commitPairs {
			if cp[0] == newCommit && cp[1] == oldCommit {
				have = true
				break
			}
		}
		if !have {
			commitPairs = append(commitPairs, RefCommitPair{newCommit, oldCommit, refPair.NewRef, refPair.OldRef})
		}
	}

	return commitPairs, nil
}