// Copyright 2020 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package gitgraph

import (
	"bytes"
	"fmt"
)

// NewGraph creates a basic graph
func NewGraph() *Graph {
	graph := &Graph{}
	graph.relationCommit = &Commit{
		Row:    -1,
		Column: -1,
	}
	graph.Flows = map[int64]*Flow{}
	return graph
}

// Graph represents a collection of flows
type Graph struct {
	Flows          map[int64]*Flow
	Commits        []*Commit
	MinRow         int
	MinColumn      int
	MaxRow         int
	MaxColumn      int
	relationCommit *Commit
}

// Width returns the width of the graph
func (graph *Graph) Width() int {
	return graph.MaxColumn - graph.MinColumn + 1
}

// Height returns the height of the graph
func (graph *Graph) Height() int {
	return graph.MaxRow - graph.MinRow + 1
}

// AddGlyph adds glyph to flows
func (graph *Graph) AddGlyph(row, column int, flowID int64, color int, glyph byte) {
	flow, ok := graph.Flows[flowID]
	if !ok {
		flow = NewFlow(flowID, color, row, column)
		graph.Flows[flowID] = flow
	}
	flow.AddGlyph(row, column, glyph)

	if row < graph.MinRow {
		graph.MinRow = row
	}
	if row > graph.MaxRow {
		graph.MaxRow = row
	}
	if column < graph.MinColumn {
		graph.MinColumn = column
	}
	if column > graph.MaxColumn {
		graph.MaxColumn = column
	}
}

// AddCommit adds a commit at row, column on flowID with the provided data
func (graph *Graph) AddCommit(row, column int, flowID int64, data []byte) error {
	commit, err := NewCommit(row, column, data)
	if err != nil {
		return err
	}
	commit.Flow = flowID
	graph.Commits = append(graph.Commits, commit)

	graph.Flows[flowID].Commits = append(graph.Flows[flowID].Commits, commit)
	return nil
}

// NewFlow creates a new flow
func NewFlow(flowID int64, color, row, column int) *Flow {
	return &Flow{
		ID:          flowID,
		ColorNumber: color,
		MinRow:      row,
		MinColumn:   column,
		MaxRow:      row,
		MaxColumn:   column,
	}
}

// Flow represents a series of glyphs
type Flow struct {
	ID          int64
	ColorNumber int
	Glyphs      []Glyph
	Commits     []*Commit
	MinRow      int
	MinColumn   int
	MaxRow      int
	MaxColumn   int
}

// Color16 wraps the color numbers around mod 16
func (flow *Flow) Color16() int {
	return flow.ColorNumber % 16
}

// AddGlyph adds glyph at row and column
func (flow *Flow) AddGlyph(row, column int, glyph byte) {
	if row < flow.MinRow {
		flow.MinRow = row
	}
	if row > flow.MaxRow {
		flow.MaxRow = row
	}
	if column < flow.MinColumn {
		flow.MinColumn = column
	}
	if column > flow.MaxColumn {
		flow.MaxColumn = column
	}

	flow.Glyphs = append(flow.Glyphs, Glyph{
		row,
		column,
		glyph,
	})
}

// Glyph represents a co-ordinate and glyph
type Glyph struct {
	Row    int
	Column int
	Glyph  byte
}

// RelationCommit represents an empty relation commit
var RelationCommit = &Commit{
	Row: -1,
}

// NewCommit creates a new commit from a provided line
func NewCommit(row, column int, line []byte) (*Commit, error) {
	data := bytes.SplitN(line, []byte("|"), 7)
	if len(data) < 7 {
		return nil, fmt.Errorf("malformed data section on line %d with commit: %s", row, string(line))
	}
	return &Commit{
		Row:    row,
		Column: column,
		// 0 matches git log --pretty=format:%d => ref names, like the --decorate option of git-log(1)
		Branch: string(data[0]),
		// 1 matches git log --pretty=format:%H => commit hash
		Rev: string(data[1]),
		// 2 matches git log --pretty=format:%ad => author date (format respects --date= option)
		Date: string(data[2]),
		// 3 matches git log --pretty=format:%an => author name
		Author: string(data[3]),
		// 4 matches git log --pretty=format:%ae => author email
		AuthorEmail: string(data[4]),
		// 5 matches git log --pretty=format:%h => abbreviated commit hash
		ShortRev: string(data[5]),
		// 6 matches git log --pretty=format:%s => subject
		Subject: string(data[6]),
	}, nil
}

// Commit represents a commit at co-ordinate X, Y with the data
type Commit struct {
	Flow        int64
	Row         int
	Column      int
	Branch      string
	Rev         string
	Date        string
	Author      string
	AuthorEmail string
	ShortRev    string
	Subject     string
}

// OnlyRelation returns whether this a relation only commit
func (c *Commit) OnlyRelation() bool {
	return c.Row == -1
}