package parsers

import (
	"errors"
	"fmt"
	"git.aiterp.net/rpdata/api/models"
	"strings"
	"time"
)

var ErrSkip = errors.New("parsers: skip this post")

func IRCCloudLogs(data string, location *time.Location, threshold time.Duration) ([]ParsedLog, error) {
	lines := strings.Split(data, "\n")
	pos := 0
	results := make([]ParsedLog, 0, 8)
	for pos < len(lines) {
		log, n, err := IRCCloudLog(lines[pos:], location, threshold)
		if err != nil {
			if err == ErrEmptyLog {
				pos += n
				continue
			}

			return nil, err
		}

		pos += n
		results = append(results, *log)
	}

	return results, nil
}

// IRCCloudLog parses the log and returns the things that can be gleamed from them.
func IRCCloudLog(lines []string, location *time.Location, threshold time.Duration) (*ParsedLog, int, error) {
	posts := make([]*models.Post, 0, len(lines))
	prev := (*models.Post)(nil)
	amount := 0

	for _, line := range lines {
		line = strings.Trim(line, "\r\t  ")
		if len(line) < 1 {
			amount += 1
			continue
		}

		post, err := IRCCloudPost(line, location)
		if err == ErrSkip {
			amount += 1
			continue
		} else if err != nil {
			return nil, -1, err
		}

		if prev != nil {
			if post.Time.Sub(prev.Time) >= threshold {
				break
			}

			post.Position = prev.Position + 1
		} else {
			post.Position = 1
		}

		posts = append(posts, &post)
		prev = &post
		amount += 1
	}

	if len(posts) == 0 {
		return nil, amount, ErrEmptyLog
	}

	log := models.Log{
		Date: posts[0].Time,
	}

	return &ParsedLog{log, posts}, amount, nil
}

// IRCCloudPost parses a post from a mirc-like line. If the previous post is included (it can be empty), it will be used
// to determine whether midnight has passed.
func IRCCloudPost(line string, tz *time.Location) (models.Post, error) {
	// Do basic validation
	line = strings.Trim(line, "  \t\n\r")
	if len(line) == 0 || !strings.HasPrefix(line, "[") {
		return models.Post{}, &ParseError{
			Line:    line,
			Problem: "no timestamp",
		}
	}

	// Parse timestamp
	tsEndIndex := strings.IndexByte(line, ']')
	if tsEndIndex == -1 || len(line) < tsEndIndex+5 {
		return models.Post{}, &ParseError{
			Line:    line,
			Problem: "incomplete timestamp",
		}
	}
	tsStr := line[1:tsEndIndex]

	ts, err := time.ParseInLocation("2006-01-02 15:04:05", tsStr, tz)
	if err != nil {
		return models.Post{}, &ParseError{
			Line:    line,
			Problem: fmt.Sprintf("Could not parse date: %s", err.Error()),
		}
	}

	if strings.HasPrefix(line[tsEndIndex+2:], "—") {
		split := strings.SplitN(line[tsEndIndex+6:], " ", 2)
		if len(split) == 1 {
			return models.Post{}, &ParseError{
				Line:    line,
				Problem: "post is empty",
			}
		}

		post := models.Post{
			ID:    "UNASSIGNED",
			LogID: "UNASSIGNED",
			Time:  ts,
			Kind:  "action",
			Nick:  strings.Trim(strings.TrimLeft(split[0], "+@!~"), "\u001F"),
			Text:  split[1],
		}

		if strings.HasPrefix(post.Nick, "=") {
			post.Kind = "scene"
		}

		return post, nil
	} else if line[tsEndIndex+2] == '<' {
		split := strings.SplitN(line[tsEndIndex+2:], " ", 2)
		if len(split) == 1 {
			return models.Post{}, &ParseError{
				Line:    line,
				Problem: "post is empty",
			}
		}

		post := models.Post{
			ID:    "UNASSIGNED",
			LogID: "UNASSIGNED",
			Time:  ts,
			Kind:  "text",
			Nick:  strings.Trim(strings.TrimLeft(split[0][1:len(split[0])-1], "+@!~"), "\u001F"),
			Text:  split[1],
		}

		if strings.HasPrefix(post.Nick, "=") {
			post.Kind = "scene"
		}

		return post, nil
	} else {
		return models.Post{}, ErrSkip
	}
}