// Package format provides chat log serialization.
//
// The chat log uses JSON Lines format: one JSON object per line.
// Each line is a complete, self-contained block.
//
// For streaming, blocks can be partial (Partial=true). The GUI shows
// partial blocks immediately; when the final block arrives (same ID,
// Partial=false), it replaces the partial version.
package format

import (
	"encoding/json"
)

// Block represents a single chat log entry.
type Block struct {
	Role    string `json:"role"`              // user, assistant, context, reasoning, call, tool, error, info, retry, stalled
	ID      string `json:"id"`                // 8-char hex block ID
	Content string `json:"content,omitempty"` // Block content (text, args for call, output for tool)
	Name    string `json:"name,omitempty"`    // Tool/function name (for call blocks)
	Format  string `json:"format,omitempty"`  // Output format hint (for tool blocks)
	Partial bool   `json:"partial,omitempty"` // True if streaming (not final)
}

// MarshalBlock returns a JSONL line for the block (with trailing newline).
func MarshalBlock(b Block) []byte {
	data, _ := json.Marshal(b)
	return append(data, '\n')
}

// UnmarshalBlock parses a JSONL line into a Block.
func UnmarshalBlock(line []byte) (Block, error) {
	var b Block
	err := json.Unmarshal(line, &b)
	return b, err
}

// RenderBlock returns human-readable text for a block (for log file).
// Partial blocks are skipped (only final blocks render).
func RenderBlock(b Block) string {
	if b.Partial {
		return ""
	}
	switch b.Role {
	case "user":
		return "You: " + b.Content + "\n\n"
	case "assistant":
		return b.Content + "\n\n"
	case "context":
		return "" // Hidden from rendered log
	case "reasoning":
		return "" // Hidden from rendered log
	case "call":
		if b.Content != "" {
			return "→ " + b.Name + " " + b.Content + "\n\n"
		}
		return "→ " + b.Name + "\n\n"
	case "tool":
		return b.Content + "\n\n"
	case "bypass":
		return "⚠ bypass requested (needs approval): " + b.Content + "\n\n"
	case "bypass-resolved":
		return "bypass " + b.Content + "\n\n"
	case "error":
		return "Error: " + b.Content + "\n\n"
	case "info":
		return "Info: " + b.Content + "\n\n"
	case "retry":
		return "Retry: " + b.Content + "\n\n"
	case "stalled":
		return "[Stalled]\n\n"
	default:
		return b.Content + "\n\n"
	}
}