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internal/modules/graph.go
4bda28df3ab3dbfcc789dcbbb184cabc8cac9398
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| 1 | package modules |
| 2 | |
| 3 | import ( |
| 4 | "fmt" |
| 5 | "html/template" |
| 6 | "strconv" |
| 7 | "strings" |
| 8 | |
| 9 | "gsg/internal/core" |
| 10 | "gsg/internal/gitx" |
| 11 | ) |
| 12 | |
| 13 | // Graph is the branch/commit DAG laid out in lanes, one row per commit. |
| 14 | // |
| 15 | // Layout runs in a single pass over --topo-order output, which guarantees a |
| 16 | // child is emitted before its parents. `active` holds, per lane, the SHA that |
| 17 | // lane is currently waiting to draw. A commit claims the lane that was |
| 18 | // expecting it (or a fresh one), hands that lane to its first parent, and |
| 19 | // opens a new lane for each additional parent -- which is exactly what makes |
| 20 | // a merge fork visually. |
| 21 | type Graph struct { |
| 22 | Rows []Row |
| 23 | Lanes int |
| 24 | |
| 25 | Ofs, PageSize int |
| 26 | HasPrev, HasNext bool |
| 27 | PrevOfs, NextOfs int |
| 28 | } |
| 29 | |
| 30 | type Row struct { |
| 31 | Commit gitx.Commit |
| 32 | Lane int |
| 33 | Refs []gitx.Ref // branch/tag tips pointing here |
| 34 | // Through are lanes that pass this row untouched (draw a full-height |
| 35 | // vertical). In are lanes merging into this commit (diagonal from the |
| 36 | // top edge to the node). Out are lanes this commit forks into |
| 37 | // (diagonal from the node to the bottom edge). |
| 38 | Through []int |
| 39 | In []int |
| 40 | Out []int |
| 41 | |
| 42 | // Rail is the row's slice of the graph, drawn as SVG. Geometry lives |
| 43 | // here because it IS the data; colour does not -- every stroke refers |
| 44 | // to a CSS custom property, so the theme still owns the palette. |
| 45 | Rail template.HTML |
| 46 | } |
| 47 | |
| 48 | func init() { core.Register("graph", graphMod) } |
| 49 | |
| 50 | // graph: the DAG across every ref. {{ mod "graph" "120" }} -- default |
| 51 | // core.GraphPageSize. Paginated via the ?ofs= query param on the graph |
| 52 | // route (see buildCtx), which core.GraphPageSize must match. |
| 53 | // |
| 54 | // Lane assignment below is a single forward pass that carries state |
| 55 | // (`active`) across every row, so a page can't be computed by slicing the |
| 56 | // git fetch with --skip -- that would reset `active` at the page boundary |
| 57 | // and corrupt lane continuity. Instead every request walks the full range |
| 58 | // from the top of history through the end of the requested page, and only |
| 59 | // the rendered rows are sliced down to the page afterward, once Lanes and |
| 60 | // each row's Rail SVG have already been computed against the full range. |
| 61 | func graphMod(c *core.Ctx, args ...string) (any, error) { |
| 62 | n := core.GraphPageSize |
| 63 | if len(args) > 0 { |
| 64 | if v, err := strconv.Atoi(args[0]); err == nil && v > 0 { |
| 65 | n = v |
| 66 | } |
| 67 | } |
| 68 | ofs, _ := strconv.Atoi(c.Var("ofs")) |
| 69 | if ofs < 0 { |
| 70 | ofs = 0 |
| 71 | } |
| 72 | commits, err := c.Repo.LogAll(ofs + n + 1) // from the top; no --skip, see above |
| 73 | if err != nil { |
| 74 | return nil, err |
| 75 | } |
| 76 | |
| 77 | tips := map[string][]gitx.Ref{} |
| 78 | if refs, err := c.Repo.Refs(); err == nil { |
| 79 | for _, r := range refs { |
| 80 | tips[r.Target] = append(tips[r.Target], r) |
| 81 | } |
| 82 | } |
| 83 | |
| 84 | var g Graph |
| 85 | var active []string // lane -> SHA that lane is waiting for ("" = free) |
| 86 | |
| 87 | for _, cm := range commits { |
| 88 | row := Row{Commit: cm, Refs: tips[cm.SHA]} |
| 89 | |
| 90 | // Every lane already expecting this commit is an incoming edge. |
| 91 | mine := -1 |
| 92 | for i, want := range active { |
| 93 | if want == cm.SHA { |
| 94 | if mine == -1 { |
| 95 | mine = i |
| 96 | } else { |
| 97 | row.In = append(row.In, i) |
| 98 | active[i] = "" // that lane terminates here |
| 99 | } |
| 100 | } |
| 101 | } |
| 102 | if mine == -1 { // a tip: no child has claimed it |
| 103 | mine = free(&active) |
| 104 | } |
| 105 | row.Lane = mine |
| 106 | |
| 107 | // Lanes untouched by this row pass straight through. |
| 108 | for i, want := range active { |
| 109 | if i != mine && want != "" && !contains(row.In, i) { |
| 110 | row.Through = append(row.Through, i) |
| 111 | } |
| 112 | } |
| 113 | |
| 114 | if len(cm.Parents) == 0 { |
| 115 | active[mine] = "" // root commit closes its lane |
| 116 | } else { |
| 117 | active[mine] = cm.Parents[0] |
| 118 | for _, p := range cm.Parents[1:] { |
| 119 | k := free(&active) |
| 120 | active[k] = p |
| 121 | row.Out = append(row.Out, k) |
| 122 | } |
| 123 | } |
| 124 | |
| 125 | if len(active) > g.Lanes { |
| 126 | g.Lanes = len(active) |
| 127 | } |
| 128 | g.Rows = append(g.Rows, row) |
| 129 | } |
| 130 | for i := range g.Rows { |
| 131 | g.Rows[i].Rail = rail(g.Rows[i], g.Lanes) |
| 132 | } |
| 133 | if g.Lanes == 0 { |
| 134 | g.Lanes = 1 |
| 135 | } |
| 136 | |
| 137 | total := len(g.Rows) |
| 138 | end := ofs + n |
| 139 | hasNext := total > end |
| 140 | if end > total { |
| 141 | end = total |
| 142 | } |
| 143 | start := ofs |
| 144 | if start > total { |
| 145 | start = total |
| 146 | } |
| 147 | g.Rows = g.Rows[start:end] |
| 148 | g.Ofs, g.PageSize = ofs, n |
| 149 | g.HasPrev, g.PrevOfs = ofs > 0, ofs-n |
| 150 | if g.PrevOfs < 0 { |
| 151 | g.PrevOfs = 0 |
| 152 | } |
| 153 | g.HasNext, g.NextOfs = hasNext, end |
| 154 | return g, nil |
| 155 | } |
| 156 | |
| 157 | // Row geometry, in px. Height must match the table row height in CSS. |
| 158 | const ( |
| 159 | laneW = 15.0 |
| 160 | rowH = 30.0 |
| 161 | radius = 3.6 |
| 162 | ) |
| 163 | |
| 164 | func lane(i int) string { return fmt.Sprintf("var(--lane-%d)", i%6) } |
| 165 | |
| 166 | func x(i int) float64 { return float64(i)*laneW + laneW/2 } |
| 167 | |
| 168 | func rail(r Row, lanes int) template.HTML { |
| 169 | var b strings.Builder |
| 170 | w := float64(lanes) * laneW |
| 171 | fmt.Fprintf(&b, `<svg class="rail-svg" width="%.0f" height="%.0f" viewBox="0 0 %.0f %.0f" aria-hidden="true">`, w, rowH, w, rowH) |
| 172 | |
| 173 | line := func(x1, y1, x2, y2 float64, c string) { |
| 174 | fmt.Fprintf(&b, `<path d="M%.1f %.1f C%.1f %.1f %.1f %.1f %.1f %.1f" stroke="%s" fill="none" stroke-width="1.6"/>`, |
| 175 | x1, y1, x1, (y1+y2)/2, x2, (y1+y2)/2, x2, y2, c) |
| 176 | } |
| 177 | |
| 178 | for _, l := range r.Through { // uninvolved lanes pass straight down |
| 179 | line(x(l), 0, x(l), rowH, lane(l)) |
| 180 | } |
| 181 | for _, l := range r.In { // merged-in lanes end at this node |
| 182 | line(x(l), 0, x(r.Lane), rowH/2, lane(l)) |
| 183 | } |
| 184 | for _, l := range r.Out { // extra parents fork away below |
| 185 | line(x(r.Lane), rowH/2, x(l), rowH, lane(l)) |
| 186 | } |
| 187 | // the commit's own lane: top half only if a child pointed here |
| 188 | line(x(r.Lane), 0, x(r.Lane), rowH/2, lane(r.Lane)) |
| 189 | line(x(r.Lane), rowH/2, x(r.Lane), rowH, lane(r.Lane)) |
| 190 | |
| 191 | fmt.Fprintf(&b, `<circle cx="%.1f" cy="%.1f" r="%.1f" fill="var(--bg)" stroke="%s" stroke-width="2"/>`, |
| 192 | x(r.Lane), rowH/2, radius, lane(r.Lane)) |
| 193 | b.WriteString(`</svg>`) |
| 194 | return template.HTML(b.String()) |
| 195 | } |
| 196 | |
| 197 | func free(active *[]string) int { |
| 198 | for i, v := range *active { |
| 199 | if v == "" { |
| 200 | return i |
| 201 | } |
| 202 | } |
| 203 | *active = append(*active, "") |
| 204 | return len(*active) - 1 |
| 205 | } |
| 206 | |
| 207 | func contains(xs []int, n int) bool { |
| 208 | for _, x := range xs { |
| 209 | if x == n { |
| 210 | return true |
| 211 | } |
| 212 | } |
| 213 | return false |
| 214 | } |