package sync

import (
	"encoding/json"
	"fmt"
	"math"
)

// ProgressData represents universal progress data with multiple location references
type ProgressData struct {
	Percentage      *float64 `json:"percentage,omitempty"`
	Epubcfi         *string  `json:"epubcfi,omitempty"`
	Character       *int64   `json:"character,omitempty"`
	Chapter         *int     `json:"chapter,omitempty"`
	ChapterProgress *float64 `json:"chapter_progress,omitempty"`
	ViewportY       *float64 `json:"viewport_y,omitempty"`
	Page            *int     `json:"page,omitempty"`
	TotalPages      *int     `json:"total_pages,omitempty"`
	PageY           *int     `json:"page_y,omitempty"`
	Zoom            *float64 `json:"zoom,omitempty"`
	ScrollX         *float64 `json:"scroll_x,omitempty"`
	ScrollY         *float64 `json:"scroll_y,omitempty"`
	Panel           *int     `json:"panel,omitempty"`
	ReadingMode     *string  `json:"reading_mode,omitempty"`
	TotalCharacters *int64   `json:"total_characters,omitempty"`
}

// DeviceProgress represents progress from a specific device
type DeviceProgress struct {
	Source    string       `json:"source"`
	Data      ProgressData `json:"data"`
	Timestamp string       `json:"timestamp,omitempty"`
}

// ConvertProgress converts progress between different format groups
func ConvertProgress(sourceFormat, targetFormat FormatGroup, sourceData map[string]interface{}) (map[string]interface{}, error) {
	percentage := extractPercentage(sourceFormat, sourceData)

	result := make(map[string]interface{})

	switch targetFormat {
	case FormatGroupReflowable:
		result["percentage"] = percentage
		if epubcfi, ok := sourceData["epubcfi"].(string); ok {
			result["epubcfi"] = epubcfi
		} else {
			// Generate approximate CFI from percentage
			result["epubcfi"] = fmt.Sprintf("epubcfi(/6/4/2:%d)", int(percentage*100))
		}
		if totalChars, ok := sourceData["total_characters"].(int64); ok {
			result["character"] = int64(float64(totalChars) * percentage)
		}

	case FormatGroupFixedLayout:
		totalPages := 200.0
		if tp, ok := sourceData["total_pages"].(int); ok {
			totalPages = float64(tp)
		}
		result["page"] = int(math.Round(percentage * totalPages))
		result["total_pages"] = int(totalPages)
		result["percentage"] = percentage
		if pageY, ok := sourceData["page_y"].(int); ok {
			result["page_y"] = pageY
		}

	case FormatGroupComicArchive:
		totalPages := 32.0
		if tp, ok := sourceData["total_pages"].(int); ok {
			totalPages = float64(tp)
		}
		result["page"] = int(math.Round(percentage * totalPages))
		result["total_pages"] = int(totalPages)
		result["percentage"] = percentage
		if panel, ok := sourceData["panel"].(int); ok {
			result["panel"] = panel
		}

	default:
		return nil, fmt.Errorf("unsupported target format: %s", targetFormat)
	}

	return result, nil
}

// extractPercentage extracts the percentage (0.0-1.0) from source data
func extractPercentage(sourceFormat FormatGroup, sourceData map[string]interface{}) float64 {
	switch sourceFormat {
	case FormatGroupReflowable:
		if p, ok := sourceData["percentage"].(float64); ok {
			return p
		}
		// Try to calculate from character offset
		if char, ok := sourceData["character"].(int64); ok {
			if total, ok := sourceData["total_characters"].(int64); ok && total > 0 {
				return float64(char) / float64(total)
			}
		}

	case FormatGroupFixedLayout, FormatGroupComicArchive:
		if page, ok := sourceData["page"].(int); ok {
			if total, ok := sourceData["total_pages"].(int); ok && total > 0 {
				return float64(page) / float64(total)
			}
		}
		// Try direct percentage
		if p, ok := sourceData["percentage"].(float64); ok {
			return p
		}
	}

	return 0.0
}

// PageToPercentage converts page/total_pages to percentage
func PageToPercentage(page, totalPages int) float64 {
	if totalPages <= 0 {
		return 0.0
	}
	percentage := float64(page) / float64(totalPages)
	if percentage > 1.0 {
		percentage = 1.0
	}
	if percentage < 0.0 {
		percentage = 0.0
	}
	return percentage
}

// PercentageToPage converts percentage to page number
func PercentageToPage(percentage float64, totalPages int) int {
	if percentage < 0.0 {
		percentage = 0.0
	}
	if percentage > 1.0 {
		percentage = 1.0
	}
	page := int(math.Round(float64(totalPages) * percentage))
	if page < 0 {
		page = 0
	}
	if page > totalPages {
		page = totalPages
	}
	return page
}

// CharacterToPercentage converts character offset to percentage
func CharacterToPercentage(character, totalCharacters int64) float64 {
	if totalCharacters <= 0 {
		return 0.0
	}
	percentage := float64(character) / float64(totalCharacters)
	if percentage > 1.0 {
		percentage = 1.0
	}
	if percentage < 0.0 {
		percentage = 0.0
	}
	return percentage
}

// PercentageToCharacter converts percentage to character offset
func PercentageToCharacter(percentage float64, totalCharacters int64) int64 {
	if percentage < 0.0 {
		percentage = 0.0
	}
	if percentage > 1.0 {
		percentage = 1.0
	}
	char := int64(math.Round(float64(totalCharacters) * percentage))
	if char < 0 {
		char = 0
	}
	if char > totalCharacters {
		char = totalCharacters
	}
	return char
}

// MergeProgress merges progress from two sources using "max progress wins" strategy
func MergeProgress(progressA, progressB map[string]interface{}) map[string]interface{} {
	percA := extractPercentage(FormatGroupReflowable, progressA)
	percB := extractPercentage(FormatGroupReflowable, progressB)

	winner := progressB
	if percA > percB {
		winner = progressA
	}

	result := make(map[string]interface{})
	for k, v := range winner {
		result[k] = v
	}

	sources := []string{}
	if srcA, ok := progressA["source"].(string); ok {
		sources = append(sources, srcA)
	}
	if srcB, ok := progressB["source"].(string); ok {
		sources = append(sources, srcB)
	}
	result["merged_from"] = sources
	result["merge_timestamp"] = "now"

	return result
}

// FormatProgressForDisplay formats progress for display based on format group
func FormatProgressForDisplay(formatGroup FormatGroup, progress map[string]interface{}) string {
	percentage := extractPercentage(formatGroup, progress)

	switch formatGroup {
	case FormatGroupReflowable:
		if chapter, ok := progress["chapter"].(int); ok {
			return fmt.Sprintf("%.1f%% (Chapter %d)", percentage*100, chapter)
		}
		return fmt.Sprintf("%.1f%%", percentage*100)

	case FormatGroupFixedLayout:
		if page, ok := progress["page"].(int); ok {
			if total, ok := progress["total_pages"].(int); ok {
				return fmt.Sprintf("Page %d of %d (%.1f%%)", page, total, percentage*100)
			}
			return fmt.Sprintf("Page %d (%.1f%%)", page, percentage*100)
		}
		return fmt.Sprintf("%.1f%%", percentage*100)

	case FormatGroupComicArchive:
		if page, ok := progress["page"].(int); ok {
			if total, ok := progress["total_pages"].(int); ok {
				return fmt.Sprintf("Page %d of %d (%.0f%%)", page, total, percentage*100)
			}
			return fmt.Sprintf("Page %d (%.0f%%)", page, percentage*100)
		}
		return fmt.Sprintf("%.0f%%", percentage*100)

	default:
		return fmt.Sprintf("%.1f%%", percentage*100)
	}
}

// ParseProgressFromJSON parses progress data from JSON
func ParseProgressFromJSON(data []byte) (*ProgressData, error) {
	var progress ProgressData
	err := json.Unmarshal(data, &progress)
	if err != nil {
		return nil, err
	}
	return &progress, nil
}

// MarshalProgressToJSON converts progress data to JSON
func MarshalProgressToJSON(progress *ProgressData) ([]byte, error) {
	return json.Marshal(progress)
}