// SPDX-License-Identifier: Apache-2.0
// Copyright Authors of Cilium

// Copyright (c) 2015, Wade Simmons
// All rights reserved.

// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:

// 1. Redistributions of source code must retain the above copyright notice, this
//    list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright notice,
//    this list of conditions and the following disclaimer in the documentation
//    and/or other materials provided with the distribution.

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// https://github.com/wadey/gocovmerge

package bpftests

import (
	"log"
	"sort"

	"golang.org/x/tools/cover"
)

func mergeProfiles(p *cover.Profile, merge *cover.Profile) {
	if p.Mode != merge.Mode {
		log.Fatalf("cannot merge profiles with different modes")
	}
	// Since the blocks are sorted, we can keep track of where the last block
	// was inserted and only look at the blocks after that as targets for merge
	startIndex := 0
	for _, b := range merge.Blocks {
		startIndex = mergeProfileBlock(p, b, startIndex)
	}
}

func mergeProfileBlock(p *cover.Profile, pb cover.ProfileBlock, startIndex int) int {
	sortFunc := func(i int) bool {
		var pi cover.ProfileBlock
		if i+startIndex < len(p.Blocks) {
			pi = p.Blocks[i+startIndex]
		} else {
			pi = p.Blocks[len(p.Blocks)-1]
		}
		return pi.StartLine >= pb.StartLine && (pi.StartLine != pb.StartLine || pi.StartCol >= pb.StartCol)
	}

	i := 0
	if !sortFunc(i) {
		i = sort.Search(len(p.Blocks)-startIndex, sortFunc)
	}
	i += startIndex
	if i < len(p.Blocks) && p.Blocks[i].StartLine == pb.StartLine && p.Blocks[i].StartCol == pb.StartCol {
		if p.Blocks[i].EndLine != pb.EndLine || p.Blocks[i].EndCol != pb.EndCol {
			log.Fatalf("OVERLAP MERGE: %v %v %v", p.FileName, p.Blocks[i], pb)
		}
		switch p.Mode {
		case "set":
			p.Blocks[i].Count |= pb.Count
		case "count", "atomic":
			p.Blocks[i].Count += pb.Count
		default:
			log.Fatalf("unsupported covermode: '%s'", p.Mode)
		}
	} else {
		if i > 0 {
			pa := p.Blocks[i-1]
			if pa.EndLine >= pb.EndLine && (pa.EndLine != pb.EndLine || pa.EndCol > pb.EndCol) {
				log.Fatalf("OVERLAP BEFORE: %v %v %v", p.FileName, pa, pb)
			}
		}
		if i < len(p.Blocks)-1 {
			pa := p.Blocks[i+1]
			if pa.StartLine <= pb.StartLine && (pa.StartLine != pb.StartLine || pa.StartCol < pb.StartCol) {
				log.Fatalf("OVERLAP AFTER: %v %v %v", p.FileName, pa, pb)
			}
		}
		p.Blocks = append(p.Blocks, cover.ProfileBlock{})
		copy(p.Blocks[i+1:], p.Blocks[i:])
		p.Blocks[i] = pb
	}
	return i + 1
}

func addProfile(profiles []*cover.Profile, p *cover.Profile) []*cover.Profile {
	i := sort.Search(len(profiles), func(i int) bool { return profiles[i].FileName >= p.FileName })
	if i < len(profiles) && profiles[i].FileName == p.FileName {
		mergeProfiles(profiles[i], p)
	} else {
		profiles = append(profiles, nil)
		copy(profiles[i+1:], profiles[i:])
		profiles[i] = p
	}
	return profiles
}
