feat: done vibing

internal/output/discord.go

@@ -0,0 +1,191 @@
+package output
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/ytshih/stonks/internal/config"
+	"github.com/ytshih/stonks/internal/report"
+)
+
+func init() {
+	Register("discord", newDiscordOutput)
+}
+
+// discordMessageLimit is Discord's max character count for a single
+// webhook message's `content` field.
+const discordMessageLimit = 2000
+
+// discordParams is the plugin-specific config for the discord output.
+type discordParams struct {
+	// WebhookEnvVar names the environment variable holding the Discord
+	// webhook URL. Defaults to DISCORD_WEBHOOK_URL.
+	WebhookEnvVar string `yaml:"webhook_env_var"`
+}
+
+// discordOutput posts the report to a Discord incoming webhook, splitting it
+// into multiple messages if it exceeds Discord's 2000-character limit.
+type discordOutput struct {
+	webhookURL string
+	client     *http.Client
+}
+
+func newDiscordOutput(cfg config.PluginConfig) (Output, error) {
+	params := discordParams{WebhookEnvVar: "DISCORD_WEBHOOK_URL"}
+	if err := cfg.DecodeParams(&params); err != nil {
+		return nil, err
+	}
+
+	url := os.Getenv(params.WebhookEnvVar)
+	if url == "" {
+		return nil, fmt.Errorf("discord: environment variable %q is not set", params.WebhookEnvVar)
+	}
+
+	return &discordOutput{
+		webhookURL: url,
+		client:     &http.Client{Timeout: 15 * time.Second},
+	}, nil
+}
+
+func (d *discordOutput) Name() string { return "discord" }
+
+func (d *discordOutput) Send(ctx context.Context, rep report.Report) error {
+	for i, chunk := range splitForDiscord(rep.Text, discordMessageLimit) {
+		if err := d.post(ctx, chunk); err != nil {
+			return fmt.Errorf("discord: send chunk %d: %w", i+1, err)
+		}
+	}
+
+	embeds := buildRecommendationEmbeds(rep.Recommendations)
+	if err := d.postEmbeds(ctx, embeds); err != nil {
+		return fmt.Errorf("discord: send recommendation embeds: %w", err)
+	}
+	return nil
+}
+
+func (d *discordOutput) post(ctx context.Context, content string) error {
+	return d.postJSON(ctx, map[string]any{"content": content})
+}
+
+func (d *discordOutput) postEmbeds(ctx context.Context, embeds []map[string]any) error {
+	return d.postJSON(ctx, map[string]any{"embeds": embeds})
+}
+
+func (d *discordOutput) postJSON(ctx context.Context, payload map[string]any) error {
+	body, err := json.Marshal(payload)
+	if err != nil {
+		return err
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, d.webhookURL, bytes.NewReader(body))
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := d.client.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode >= 300 {
+		respBody, _ := io.ReadAll(resp.Body)
+		return fmt.Errorf("unexpected status %d: %s", resp.StatusCode, string(respBody))
+	}
+	return nil
+}
+
+// Discord embed colors (decimal RGB).
+const (
+	colorBuy  = 0x57F287 // green
+	colorSell = 0xED4245 // red
+)
+
+// discordDescriptionLimit is Discord's max character count for a single
+// embed's `description`.
+const discordDescriptionLimit = 4096
+
+// buildRecommendationEmbeds renders the buy and sell recommendations as two
+// separate Discord embeds (always both, even when one or both lists are
+// empty, so "nothing to report" is stated explicitly rather than omitted).
+func buildRecommendationEmbeds(recs []report.Recommendation) []map[string]any {
+	var buyLines, sellLines []string
+	for _, r := range recs {
+		line := fmt.Sprintf("**%s** — %s", r.Symbol, r.Reason)
+		if r.Action == "sell" {
+			sellLines = append(sellLines, line)
+		} else {
+			buyLines = append(buyLines, line)
+		}
+	}
+
+	return []map[string]any{
+		recommendationEmbed("🟢 Buy", colorBuy, buyLines, "No buy recommendations today."),
+		recommendationEmbed("🔴 Sell", colorSell, sellLines, "No sell recommendations today."),
+	}
+}
+
+func recommendationEmbed(title string, color int, lines []string, emptyText string) map[string]any {
+	description := emptyText
+	if len(lines) > 0 {
+		description = truncateForDescription(strings.Join(lines, "\n"))
+	}
+	return map[string]any{
+		"title":       title,
+		"color":       color,
+		"description": description,
+	}
+}
+
+func truncateForDescription(s string) string {
+	if len(s) <= discordDescriptionLimit {
+		return s
+	}
+	return s[:discordDescriptionLimit-3] + "..."
+}
+
+// splitForDiscord breaks text into chunks of at most limit characters,
+// preferring to split on paragraph/line boundaries so Markdown formatting
+// stays intact across messages.
+func splitForDiscord(text string, limit int) []string {
+	if len(text) <= limit {
+		return []string{text}
+	}
+
+	var chunks []string
+	var current strings.Builder
+
+	flush := func() {
+		if current.Len() > 0 {
+			chunks = append(chunks, strings.TrimSpace(current.String()))
+			current.Reset()
+		}
+	}
+
+	for _, line := range strings.Split(text, "\n") {
+		// A single line longer than the limit must be hard-split.
+		for len(line) > limit {
+			if current.Len() > 0 {
+				flush()
+			}
+			chunks = append(chunks, line[:limit])
+			line = line[limit:]
+		}
+		if current.Len()+len(line)+1 > limit {
+			flush()
+		}
+		current.WriteString(line)
+		current.WriteString("\n")
+	}
+	flush()
+
+	return chunks
+}