package topdata

import (
	"fmt"
	"path/filepath"
	"slices"
	"strconv"
	"strings"
)

type classSpellbookSpec struct {
	Path   string
	Key    string
	Class  string
	Levels map[int][]string
}

type classSpellbookPlan struct {
	Spec        classSpellbookSpec
	Column      string
	SpellLevels map[string]int
}

func isClassSpellbookPath(path string) bool {
	slashed := filepath.ToSlash(path)
	return strings.Contains(slashed, "/data/classes/spellbooks/") && strings.HasSuffix(strings.ToLower(slashed), ".json")
}

func validateClassSpellbookShape(path string, obj map[string]any, report *ValidationReport) {
	if _, ok := obj["class"]; !ok {
		report.Diagnostics = append(report.Diagnostics, Diagnostic{Severity: SeverityError, Path: path, Message: "class spellbook requires class"})
	}
	if _, ok := obj["levels"]; !ok {
		report.Diagnostics = append(report.Diagnostics, Diagnostic{Severity: SeverityError, Path: path, Message: "class spellbook requires levels"})
	}
}

func validateClassSpellbooks(dataDir string, report *ValidationReport) {
	collected, err := collectSpellbookValidationDatasets(dataDir)
	if err != nil {
		report.Diagnostics = append(report.Diagnostics, Diagnostic{
			Severity: SeverityError,
			Path:     dataDir,
			Message:  fmt.Sprintf("validate class spellbooks: %v", err),
		})
		return
	}
	_, diagnostics := classSpellbookPlans(dataDir, collected)
	report.Diagnostics = append(report.Diagnostics, diagnostics...)
}

func collectSpellbookValidationDatasets(dataDir string) ([]nativeCollectedDataset, error) {
	datasets, err := discoverNativeDatasets(dataDir)
	if err != nil {
		return nil, err
	}
	out := make([]nativeCollectedDataset, 0, 2)
	for _, dataset := range datasets {
		if dataset.Name != "classes/core" && dataset.Name != "spells" {
			continue
		}
		collected, err := collectNativeDataset(dataset)
		if err != nil {
			return nil, err
		}
		out = append(out, collected)
	}
	return out, nil
}

func applyClassSpellbooks(sourceDir string, collected []nativeCollectedDataset) ([]nativeCollectedDataset, error) {
	dataDir := filepath.Join(sourceDir, "data")
	plans, diagnostics := classSpellbookPlans(dataDir, collected)
	if len(diagnostics) > 0 {
		return nil, fmt.Errorf("class spellbook validation failed: %s", diagnosticsTextForError(diagnostics))
	}
	if len(plans) == 0 {
		return collected, nil
	}

	out := make([]nativeCollectedDataset, len(collected))
	copy(out, collected)
	spellsIndex := -1
	for index := range out {
		if out[index].Dataset.Name == "spells" {
			spellsIndex = index
			break
		}
	}
	if spellsIndex == -1 {
		return nil, fmt.Errorf("class spellbooks require canonical dataset %q", "spells")
	}

	spells := out[spellsIndex]
	columns := append([]string(nil), spells.Columns...)
	rows := make([]map[string]any, 0, len(spells.Rows))
	for _, row := range spells.Rows {
		rows = append(rows, cloneRowMap(row))
	}
	rowByKey := rowsByKey(rows)

	for _, plan := range plans {
		column := plan.Column
		if _, ok := canonicalColumn(columns, column); !ok {
			columns = append(columns, column)
			ensureRowsExposeColumns(rows, columns)
		}
		for _, row := range rows {
			row[column] = nullValue
		}
		for spellKey, level := range plan.SpellLevels {
			row := rowByKey[spellKey]
			if row == nil {
				return nil, fmt.Errorf("%s: unknown spell %q", plan.Spec.Path, spellKey)
			}
			row[column] = level
		}
	}

	spells.Columns = columns
	spells.Rows = rows
	out[spellsIndex] = spells
	return out, nil
}

func classSpellbookPlans(dataDir string, collected []nativeCollectedDataset) ([]classSpellbookPlan, []Diagnostic) {
	specs, diagnostics := loadClassSpellbookSpecs(filepath.Join(dataDir, "classes", "spellbooks"))
	if len(specs) == 0 {
		return nil, diagnostics
	}
	classes := collectedDatasetByName(collected, "classes/core")
	spells := collectedDatasetByName(collected, "spells")
	if classes == nil {
		diagnostics = append(diagnostics, Diagnostic{Severity: SeverityError, Path: dataDir, Message: `class spellbooks require canonical dataset "classes/core"`})
		return nil, diagnostics
	}
	if spells == nil {
		diagnostics = append(diagnostics, Diagnostic{Severity: SeverityError, Path: dataDir, Message: `class spellbooks require canonical dataset "spells"`})
		return nil, diagnostics
	}

	classRows := rowsByKey(classes.Rows)
	spellRows := rowsByKey(spells.Rows)
	seenColumns := map[string]string{}
	plans := make([]classSpellbookPlan, 0, len(specs))
	for _, spec := range specs {
		classRow := classRows[spec.Class]
		if classRow == nil {
			diagnostics = append(diagnostics, Diagnostic{Severity: SeverityError, Path: spec.Path, Message: fmt.Sprintf("unknown class %q", spec.Class)})
		}
		column := ""
		if classRow != nil {
			column, _ = classRow["SpellTableColumn"].(string)
			column = strings.TrimSpace(column)
			if column == "" || column == nullValue {
				diagnostics = append(diagnostics, Diagnostic{Severity: SeverityError, Path: spec.Path, Message: fmt.Sprintf("class %q has no SpellTableColumn", spec.Class)})
			}
		}
		if column != "" && column != nullValue {
			folded := strings.ToLower(column)
			if previous, ok := seenColumns[folded]; ok {
				diagnostics = append(diagnostics, Diagnostic{Severity: SeverityError, Path: spec.Path, Message: fmt.Sprintf("SpellTableColumn %q is already managed by %s", column, previous)})
			} else {
				seenColumns[folded] = spec.Path
			}
		}

		spellLevels := map[string]int{}
		for _, level := range sortedIntKeys(spec.Levels) {
			for _, spellKey := range spec.Levels[level] {
				if spellRows[spellKey] == nil {
					diagnostics = append(diagnostics, Diagnostic{Severity: SeverityError, Path: spec.Path, Message: fmt.Sprintf("unknown spell %q", spellKey)})
					continue
				}
				if previous, ok := spellLevels[spellKey]; ok {
					diagnostics = append(diagnostics, Diagnostic{Severity: SeverityError, Path: spec.Path, Message: fmt.Sprintf("spell %q appears at both level %d and level %d", spellKey, previous, level)})
					continue
				}
				spellLevels[spellKey] = level
			}
		}

		if column != "" && column != nullValue {
			plans = append(plans, classSpellbookPlan{Spec: spec, Column: column, SpellLevels: spellLevels})
		}
	}
	return plans, diagnostics
}

func loadClassSpellbookSpecs(dir string) ([]classSpellbookSpec, []Diagnostic) {
	paths, err := collectModulePaths(dir)
	if err != nil {
		return nil, []Diagnostic{{Severity: SeverityError, Path: dir, Message: err.Error()}}
	}
	specs := make([]classSpellbookSpec, 0, len(paths))
	diagnostics := []Diagnostic{}
	for _, path := range paths {
		obj, err := loadJSONObject(path)
		if err != nil {
			diagnostics = append(diagnostics, Diagnostic{Severity: SeverityError, Path: path, Message: err.Error()})
			continue
		}
		spec, specDiagnostics := parseClassSpellbookSpec(path, obj)
		diagnostics = append(diagnostics, specDiagnostics...)
		if spec.Class != "" && spec.Levels != nil {
			specs = append(specs, spec)
		}
	}
	return specs, diagnostics
}

func parseClassSpellbookSpec(path string, obj map[string]any) (classSpellbookSpec, []Diagnostic) {
	diagnostics := []Diagnostic{}
	spec := classSpellbookSpec{Path: path, Levels: map[int][]string{}}
	if key, ok := obj["key"].(string); ok {
		spec.Key = strings.TrimSpace(key)
	}
	classKey, ok := obj["class"].(string)
	if !ok || strings.TrimSpace(classKey) == "" {
		diagnostics = append(diagnostics, Diagnostic{Severity: SeverityError, Path: path, Message: "class spellbook requires class"})
	} else {
		spec.Class = strings.TrimSpace(classKey)
		if !strings.HasPrefix(spec.Class, "classes:") {
			diagnostics = append(diagnostics, Diagnostic{Severity: SeverityError, Path: path, Message: "class must use a classes: reference"})
		}
	}
	rawLevels, ok := obj["levels"].(map[string]any)
	if !ok {
		diagnostics = append(diagnostics, Diagnostic{Severity: SeverityError, Path: path, Message: "class spellbook levels must be an object"})
		return spec, diagnostics
	}
	for _, rawLevel := range sortedKeys(rawLevels) {
		level, err := strconv.Atoi(rawLevel)
		if err != nil || level < 0 {
			diagnostics = append(diagnostics, Diagnostic{Severity: SeverityError, Path: path, Message: fmt.Sprintf("level key %q must be a nonnegative integer", rawLevel)})
			continue
		}
		rawList, ok := rawLevels[rawLevel].([]any)
		if !ok {
			diagnostics = append(diagnostics, Diagnostic{Severity: SeverityError, Path: path, Message: fmt.Sprintf("level %d must be an array", level)})
			continue
		}
		for index, rawSpell := range rawList {
			spellKey, ok := rawSpell.(string)
			if !ok || strings.TrimSpace(spellKey) == "" {
				diagnostics = append(diagnostics, Diagnostic{Severity: SeverityError, Path: path, Message: fmt.Sprintf("level %d spell %d must be a spells: reference", level, index)})
				continue
			}
			spellKey = strings.TrimSpace(spellKey)
			if !strings.HasPrefix(spellKey, "spells:") {
				diagnostics = append(diagnostics, Diagnostic{Severity: SeverityError, Path: path, Message: fmt.Sprintf("level %d spell %d must use a spells: reference", level, index)})
				continue
			}
			spec.Levels[level] = append(spec.Levels[level], spellKey)
		}
	}
	return spec, diagnostics
}

func collectedDatasetByName(collected []nativeCollectedDataset, name string) *nativeCollectedDataset {
	for index := range collected {
		if collected[index].Dataset.Name == name {
			return &collected[index]
		}
	}
	return nil
}

func rowsByKey(rows []map[string]any) map[string]map[string]any {
	out := make(map[string]map[string]any, len(rows))
	for _, row := range rows {
		key, _ := row["key"].(string)
		if key != "" {
			out[key] = row
		}
	}
	return out
}

func sortedIntKeys(values map[int][]string) []int {
	keys := make([]int, 0, len(values))
	for key := range values {
		keys = append(keys, key)
	}
	slices.Sort(keys)
	return keys
}

func diagnosticsTextForError(diags []Diagnostic) string {
	messages := make([]string, 0, len(diags))
	for _, diag := range diags {
		messages = append(messages, diag.Message)
	}
	return strings.Join(messages, "; ")
}