zfin/src/chart_export.zig
2026-05-19 14:18:53 -07:00

236 lines
8 KiB
Zig

//! Chart-to-PNG export.
//!
//! The CLI's `--export-chart <path>` flag funnels through this
//! module. Each chart-bearing command (`quote`, `projections`)
//! has a corresponding `export*` function here that:
//!
//! 1. Calls the relevant `renderToSurface` (in `tui/chart.zig` or
//! `tui/projection_chart.zig`) to draw the chart into a z2d
//! `Surface`.
//! 2. Calls `z2d.png_exporter.writeToPNGFile` to land the surface
//! as a PNG file at the user-supplied path.
//! 3. Frees the surface.
//!
//! Default export resolution is 1920x1080 — matches the TUI's
//! `chart_config.max_width`/`max_height` defaults so the exported
//! image has the same fidelity the user sees in the terminal.
//! The TUI's adaptive chart sizing isn't used here because the
//! export target is a file, not a cell grid.
//!
//! The module deliberately reuses the TUI's `default_theme` for
//! consistent visual identity across the live TUI surface and
//! exported images. A `--theme` override at export time is out of
//! scope for V1 (see TODO follow-up).
const std = @import("std");
const z2d = @import("z2d");
const zfin = @import("root.zig");
const chart = @import("tui/chart.zig");
const projection_chart = @import("tui/projection_chart.zig");
const projections = @import("analytics/projections.zig");
const theme = @import("tui/theme.zig");
/// Default PNG export resolution. Matches `tui/chart.zig`'s
/// `ChartConfig.max_width/max_height` defaults so an exported
/// image carries the same fidelity as a maximally-sized TUI
/// chart.
pub const default_width: u32 = 1920;
pub const default_height: u32 = 1080;
/// Export a price+Bollinger+RSI chart for a single symbol.
/// Wraps `chart.renderToSurface` + `writeToPNGFile`.
pub fn exportSymbolChart(
io: std.Io,
alloc: std.mem.Allocator,
candles: []const zfin.Candle,
timeframe: chart.Timeframe,
path: []const u8,
) !void {
var rendered = chart.renderToSurface(
io,
alloc,
candles,
timeframe,
default_width,
default_height,
theme.default_theme,
null,
) catch |err| switch (err) {
error.InsufficientData => return error.InsufficientData,
else => return err,
};
defer rendered.deinit(alloc);
try z2d.png_exporter.writeToPNGFile(io, rendered.surface, path, .{});
}
/// Export a projection percentile-band chart with optional actuals
/// overlay. Wraps `projection_chart.renderToSurface` +
/// `writeToPNGFile`.
pub fn exportProjectionChart(
io: std.Io,
alloc: std.mem.Allocator,
bands: []const projections.YearPercentiles,
actuals: ?projection_chart.ActualsOverlay,
path: []const u8,
) !void {
var rendered = projection_chart.renderToSurface(
io,
alloc,
bands,
default_width,
default_height,
theme.default_theme,
actuals,
) catch |err| switch (err) {
error.InsufficientData => return error.InsufficientData,
else => return err,
};
defer rendered.deinit(alloc);
try z2d.png_exporter.writeToPNGFile(io, rendered.surface, path, .{});
}
// ── Tests ─────────────────────────────────────────────────────────────
test "exportSymbolChart writes a non-empty PNG file" {
const Date = @import("Date.zig");
const alloc = std.testing.allocator;
const io = std.testing.io;
// Minimum candle count (renderToSurface requires >= 20)
var candles: [25]zfin.Candle = undefined;
for (0..25) |i| {
const price: f64 = 100.0 + @as(f64, @floatFromInt(i));
candles[i] = .{
.date = Date.fromYmd(2024, 1, 2).addDays(@intCast(i)),
.open = price,
.high = price + 1,
.low = price - 1,
.close = price,
.adj_close = price,
.volume = 1000,
};
}
var tmp = std.testing.tmpDir(.{});
defer tmp.cleanup();
var path_buf: [std.fs.max_path_bytes]u8 = undefined;
const dir_len = try tmp.dir.realPathFile(io, ".", &path_buf);
const dir_path = path_buf[0..dir_len];
const path = try std.fs.path.join(alloc, &.{ dir_path, "test_export_symbol.png" });
defer alloc.free(path);
try exportSymbolChart(io, alloc, &candles, .@"6M", path);
// Verify the file exists, starts with the PNG magic, and is
// big enough to plausibly contain a chart (not just headers).
var file = try tmp.dir.openFile(io, "test_export_symbol.png", .{});
defer file.close(io);
const size = (try file.stat(io)).size;
try std.testing.expect(size > 1024); // arbitrary lower bound
var magic: [8]u8 = undefined;
var reader = file.reader(io, &.{});
_ = try reader.interface.readSliceShort(&magic);
try std.testing.expectEqualSlices(u8, "\x89PNG\x0D\x0A\x1A\x0A", &magic);
}
test "exportSymbolChart returns InsufficientData on too-few candles" {
const Date = @import("Date.zig");
const alloc = std.testing.allocator;
const io = std.testing.io;
var candles: [10]zfin.Candle = undefined;
for (0..10) |i| {
candles[i] = .{
.date = Date.fromYmd(2024, 1, 2).addDays(@intCast(i)),
.open = 100,
.high = 100,
.low = 100,
.close = 100,
.adj_close = 100,
.volume = 0,
};
}
var tmp = std.testing.tmpDir(.{});
defer tmp.cleanup();
var path_buf: [std.fs.max_path_bytes]u8 = undefined;
const dir_len = try tmp.dir.realPathFile(io, ".", &path_buf);
const dir_path = path_buf[0..dir_len];
const path = try std.fs.path.join(alloc, &.{ dir_path, "test_export_symbol_insufficient.png" });
defer alloc.free(path);
try std.testing.expectError(
error.InsufficientData,
exportSymbolChart(io, alloc, &candles, .@"6M", path),
);
}
test "exportProjectionChart writes a non-empty PNG file" {
const alloc = std.testing.allocator;
const io = std.testing.io;
// Synthetic 11-year horizon: bands grow linearly, all
// percentiles spread around p50.
var bands: [11]projections.YearPercentiles = undefined;
for (0..11) |i| {
const base: f64 = 100_000.0 * (1.0 + 0.07 * @as(f64, @floatFromInt(i)));
bands[i] = .{
.year = @intCast(i),
.p10 = base * 0.6,
.p25 = base * 0.8,
.p50 = base,
.p75 = base * 1.2,
.p90 = base * 1.5,
};
}
var tmp = std.testing.tmpDir(.{});
defer tmp.cleanup();
var path_buf: [std.fs.max_path_bytes]u8 = undefined;
const dir_len = try tmp.dir.realPathFile(io, ".", &path_buf);
const dir_path = path_buf[0..dir_len];
const path = try std.fs.path.join(alloc, &.{ dir_path, "test_export_projection.png" });
defer alloc.free(path);
try exportProjectionChart(io, alloc, &bands, null, path);
var file = try tmp.dir.openFile(io, "test_export_projection.png", .{});
defer file.close(io);
const size = (try file.stat(io)).size;
try std.testing.expect(size > 1024);
var magic: [8]u8 = undefined;
var reader = file.reader(io, &.{});
_ = try reader.interface.readSliceShort(&magic);
try std.testing.expectEqualSlices(u8, "\x89PNG\x0D\x0A\x1A\x0A", &magic);
}
test "exportProjectionChart returns InsufficientData with single band" {
const alloc = std.testing.allocator;
const io = std.testing.io;
var bands: [1]projections.YearPercentiles = .{.{
.year = 0,
.p10 = 100,
.p25 = 110,
.p50 = 120,
.p75 = 130,
.p90 = 140,
}};
var tmp = std.testing.tmpDir(.{});
defer tmp.cleanup();
var path_buf: [std.fs.max_path_bytes]u8 = undefined;
const dir_len = try tmp.dir.realPathFile(io, ".", &path_buf);
const dir_path = path_buf[0..dir_len];
const path = try std.fs.path.join(alloc, &.{ dir_path, "test_export_projection_insufficient.png" });
defer alloc.free(path);
try std.testing.expectError(
error.InsufficientData,
exportProjectionChart(io, alloc, &bands, null, path),
);
}