package gust

import (
	"bufio"
	"math"
	"os"
	"sort"
	"strconv"
)

type Fs map[string]Lines
type Lines map[int]string

func BuildFs(messages []CompilerMessage) Fs {
	files := make(Fs)
	for _, msg := range messages {
		if msg.Location.File != "" {
			files[msg.Location.File] = nil
		}
	}

	for f := range files {
		fd, err := os.Open(f)
		if err != nil {
			// failed to open file
			continue
		}

		lines := make(Lines)
		scanner := bufio.NewScanner(fd)
		nr := 1
		for scanner.Scan() {
			lines[nr] = scanner.Text()
			nr++
		}

		if err := scanner.Err(); err != nil {
			continue
		}

		files[f] = lines
	}

	return files
}

func (lines Lines) Start() int {
	start := math.MaxInt
	for lineNum := range lines {
		start = min(start, lineNum)
	}
	return start
}

func (lines Lines) Ordered() []string {
	lineNumbers := make([]int, 0, len(lines))
	for lineNum := range lines {
		lineNumbers = append(lineNumbers, lineNum)
	}

	sort.Ints(lineNumbers)

	ordered := []string{}
	for _, nr := range lineNumbers {
		ordered = append(ordered, lines[nr])
	}

	return ordered
}

func (fs *Fs) PopulateContext(msgs []CompilerMessage, ctxSize int) {
	for i, m := range msgs {
		path := m.Location.File
		file, _ := (*fs)[path]
		line := m.Location.Line

		if path != "" && line != "" {
			nr, _ := strconv.Atoi(line)
			ctx := make(Lines)
			for i := nr - ctxSize; i <= nr+ctxSize; i++ {
				if l, ok := file[i]; ok {
					ctx[i] = l
				}
			}

			// extract lines
			msgs[i].Context = ctx
		}
	}
}