package analyze

import (
	"encoding/json"
	"fmt"
	"strings"

	"gitea.konchin.com/service/stonks/internal/report"
)

// recommendationsMarker must match the marker text SystemPrompt instructs
// Claude to emit before the trailing recommendations JSON block.
const recommendationsMarker = "===RECOMMENDATIONS_JSON==="

type recommendationsPayload struct {
	Recommendations []report.Recommendation `json:"recommendations"`
}

// SplitReport separates Claude's raw response into the long-form narrative
// text and the short buy/sell recommendations list appended after
// recommendationsMarker (see SystemPrompt).
//
// If the marker is missing or the trailing JSON fails to parse, the full raw
// text is returned as-is with a nil recommendations slice, plus a non-nil
// error — callers should log it as a warning and still send the text-only
// report rather than treat this as fatal.
func SplitReport(raw string) (report.Report, error) {
	idx := strings.Index(raw, recommendationsMarker)
	if idx == -1 {
		return report.Report{Text: strings.TrimSpace(raw)},
			fmt.Errorf("recommendations marker not found in response")
	}

	text := strings.TrimSpace(raw[:idx])
	jsonPart := extractJSONObject(raw[idx+len(recommendationsMarker):])

	var payload recommendationsPayload
	if err := json.Unmarshal([]byte(jsonPart), &payload); err != nil {
		return report.Report{Text: text}, fmt.Errorf("parse recommendations json: %w", err)
	}

	for _, r := range payload.Recommendations {
		if r.Action != "buy" && r.Action != "sell" {
			return report.Report{Text: text}, fmt.Errorf("recommendation for %q has invalid action %q", r.Symbol, r.Action)
		}
	}

	return report.Report{Text: text, Recommendations: payload.Recommendations}, nil
}

// extractJSONObject pulls out the substring from the first "{" to the last
// "}" in s. This tolerates any decoration Claude adds around the JSON
// despite being asked not to — a ```json fence, a stray leading backtick, a
// trailing sentence — since none of that can contain a brace that comes
// before the real opening one or after the real closing one. Returns s
// trimmed, unchanged, if no braces are found (json.Unmarshal will then fail
// with a clear error).
func extractJSONObject(s string) string {
	start := strings.IndexByte(s, '{')
	end := strings.LastIndexByte(s, '}')
	if start == -1 || end == -1 || end < start {
		return strings.TrimSpace(s)
	}
	return s[start : end+1]
}