package channelmemory

import (
	"encoding/json"
	"regexp"
	"slices"
	"strings"
	"time"
)

var DefaultAllowedTypes = []string{"people", "projects", "decisions", "todos", "preferences", "events"}

const maxCustomPromptChars = 4000

const GlobalCustomPromptConfigKey = "channel_memory.extraction.custom_prompt"

type Config struct {
	Enabled            bool              `json:"enabled"`
	ReviewMode         bool              `json:"review_mode"`
	IntervalMinutes    int               `json:"interval_minutes"`
	MessageCap         int               `json:"message_cap"`
	RetentionHours     int               `json:"retention_hours"`
	AllowedTypes       []string          `json:"allowed_types"`
	ExcludeUsers       []string          `json:"exclude_users"`
	ExcludePatterns    []string          `json:"exclude_patterns"`
	ExcludeHistoryKeys []string          `json:"exclude_history_keys"`
	CustomPrompt       string            `json:"custom_prompt"`
	GroupCustomPrompts map[string]string `json:"group_custom_prompts"`
	MinMessages        int               `json:"min_messages"`
	GroupOnly          bool              `json:"group_only"`
}

type ConfigPatch struct {
	Enabled            *bool              `json:"enabled"`
	ReviewMode         *bool              `json:"review_mode"`
	IntervalMinutes    *int               `json:"interval_minutes"`
	MessageCap         *int               `json:"message_cap"`
	RetentionHours     *int               `json:"retention_hours"`
	AllowedTypes       *[]string          `json:"allowed_types"`
	ExcludeUsers       *[]string          `json:"exclude_users"`
	ExcludePatterns    *[]string          `json:"exclude_patterns"`
	ExcludeHistoryKeys *[]string          `json:"exclude_history_keys"`
	CustomPrompt       *string            `json:"custom_prompt"`
	GroupCustomPrompts *map[string]string `json:"group_custom_prompts"`
	MinMessages        *int               `json:"min_messages"`
	GroupOnly          *bool              `json:"group_only"`
}

func DefaultConfig() Config {
	return Config{
		Enabled:         false,
		ReviewMode:      true,
		IntervalMinutes: 360,
		MessageCap:      100,
		RetentionHours:  168,
		AllowedTypes:    slices.Clone(DefaultAllowedTypes),
		MinMessages:     5,
		GroupOnly:       true,
	}
}

func ParseConfig(raw json.RawMessage) Config {
	cfg := DefaultConfig()
	if len(raw) == 0 {
		return cfg
	}
	var root struct {
		PassiveMemory *Config `json:"passive_memory"`
	}
	if err := json.Unmarshal(raw, &root); err != nil || root.PassiveMemory == nil {
		return cfg
	}
	in := root.PassiveMemory
	cfg.Enabled = in.Enabled
	cfg.ReviewMode = in.ReviewMode
	cfg.IntervalMinutes = clampInt(in.IntervalMinutes, 15, 10080, cfg.IntervalMinutes)
	cfg.MessageCap = clampInt(in.MessageCap, 10, 1000, cfg.MessageCap)
	cfg.RetentionHours = clampInt(in.RetentionHours, 1, 720, cfg.RetentionHours)
	cfg.AllowedTypes = normalizeAllowedTypes(in.AllowedTypes)
	cfg.ExcludeUsers = boundedStrings(in.ExcludeUsers, 50, 255)
	cfg.ExcludePatterns = boundedPatterns(in.ExcludePatterns, 20, 255)
	cfg.ExcludeHistoryKeys = boundedStrings(in.ExcludeHistoryKeys, 200, 255)
	cfg.CustomPrompt = normalizeCustomPrompt(in.CustomPrompt)
	cfg.GroupCustomPrompts = normalizeGroupCustomPrompts(in.GroupCustomPrompts)
	cfg.MinMessages = clampInt(in.MinMessages, 2, 100, cfg.MinMessages)
	cfg.GroupOnly = true
	return cfg
}

func ApplyConfigPatch(base Config, raw []byte) (Config, error) {
	var patch ConfigPatch
	if err := json.Unmarshal(raw, &patch); err != nil {
		return Config{}, err
	}
	cfg := base
	if patch.Enabled != nil {
		cfg.Enabled = *patch.Enabled
	}
	if patch.ReviewMode != nil {
		cfg.ReviewMode = *patch.ReviewMode
	}
	if patch.IntervalMinutes != nil {
		cfg.IntervalMinutes = *patch.IntervalMinutes
	}
	if patch.MessageCap != nil {
		cfg.MessageCap = *patch.MessageCap
	}
	if patch.RetentionHours != nil {
		cfg.RetentionHours = *patch.RetentionHours
	}
	if patch.AllowedTypes != nil {
		cfg.AllowedTypes = *patch.AllowedTypes
	}
	if patch.ExcludeUsers != nil {
		cfg.ExcludeUsers = *patch.ExcludeUsers
	}
	if patch.ExcludePatterns != nil {
		cfg.ExcludePatterns = *patch.ExcludePatterns
	}
	if patch.ExcludeHistoryKeys != nil {
		cfg.ExcludeHistoryKeys = *patch.ExcludeHistoryKeys
	}
	if patch.CustomPrompt != nil {
		cfg.CustomPrompt = *patch.CustomPrompt
	}
	if patch.GroupCustomPrompts != nil {
		cfg.GroupCustomPrompts = *patch.GroupCustomPrompts
	}
	if patch.MinMessages != nil {
		cfg.MinMessages = *patch.MinMessages
	}
	if patch.GroupOnly != nil {
		cfg.GroupOnly = *patch.GroupOnly
	}
	return ParseConfig(MergeIntoInstanceConfig(nil, cfg)), nil
}

func ApplyInstanceConfigPatch(raw json.RawMessage, patch []byte) (json.RawMessage, Config, error) {
	cfg, err := ApplyConfigPatch(ParseConfig(raw), patch)
	if err != nil {
		return nil, Config{}, err
	}
	return MergeIntoInstanceConfig(raw, cfg), cfg, nil
}

func MergeIntoInstanceConfig(raw json.RawMessage, cfg Config) json.RawMessage {
	var root map[string]any
	if len(raw) == 0 || json.Unmarshal(raw, &root) != nil || root == nil {
		root = make(map[string]any)
	}
	root["passive_memory"] = cfg
	out, _ := json.Marshal(root)
	return out
}

func (c Config) Interval() time.Duration {
	return time.Duration(c.IntervalMinutes) * time.Minute
}

func normalizeAllowedTypes(in []string) []string {
	allowed := make([]string, 0, len(DefaultAllowedTypes))
	for _, v := range in {
		if slices.Contains(DefaultAllowedTypes, v) && !slices.Contains(allowed, v) {
			allowed = append(allowed, v)
		}
	}
	if len(allowed) == 0 {
		return slices.Clone(DefaultAllowedTypes)
	}
	return allowed
}

func boundedStrings(in []string, maxCount, maxLen int) []string {
	out := make([]string, 0, min(len(in), maxCount))
	for _, v := range in {
		v = strings.TrimSpace(v)
		if v == "" || len(v) > maxLen {
			continue
		}
		out = append(out, v)
		if len(out) >= maxCount {
			break
		}
	}
	return out
}

func boundedPatterns(in []string, maxCount, maxLen int) []string {
	candidates := boundedStrings(in, maxCount, maxLen)
	out := candidates[:0]
	for _, v := range candidates {
		if _, err := regexp.Compile(v); err == nil {
			out = append(out, v)
		}
	}
	return out
}

func clampInt(v, minV, maxV, fallback int) int {
	if v == 0 {
		return fallback
	}
	if v < minV {
		return minV
	}
	if v > maxV {
		return maxV
	}
	return v
}

func normalizeCustomPrompt(v string) string {
	v = strings.TrimSpace(v)
	if len([]rune(v)) > maxCustomPromptChars {
		v = string([]rune(v)[:maxCustomPromptChars])
	}
	return v
}

func normalizeGroupCustomPrompts(in map[string]string) map[string]string {
	if len(in) == 0 {
		return nil
	}
	out := make(map[string]string, min(len(in), 200))
	for key, value := range in {
		key = strings.TrimSpace(key)
		if key == "" || len(key) > 255 {
			continue
		}
		value = normalizeCustomPrompt(value)
		if value == "" {
			continue
		}
		out[key] = value
		if len(out) >= 200 {
			break
		}
	}
	if len(out) == 0 {
		return nil
	}
	return out
}