package agent

import (
	"encoding/json"
	"os"
	"path/filepath"
	"strings"
	"sync"

	"ollie/embedding"
	"ollie/skills"
	"ollie/util"
)

// Skill matching configuration.
const (
	// skillMatchThreshold is the minimum cosine similarity to include a skill.
	skillMatchThreshold = 0.35
	// skillMatchLimit is the maximum number of skills to inject per turn.
	skillMatchLimit = 3

	// toolMatchThreshold is the minimum cosine similarity to include a tool hint.
	toolMatchThreshold = 0.35
	// toolMatchLimit is the maximum number of tool hints to inject per turn.
	toolMatchLimit = 5
)

var (
	skillIndex   *skills.Index
	skillInitErr error
	skillOnce    sync.Once

	toolIndex   *skills.Index
	toolInitErr error
	toolOnce    sync.Once
)

// matchSkills finds skills relevant to the user's input and returns
// their content formatted for injection. Initializes the skill index
// on first call.
func matchSkills(input string) string {
	skillOnce.Do(func() {
		idx, err := skills.NewIndex(skills.DefaultModelDir(), skills.DefaultSkillDirs())
		if err != nil {
			skillInitErr = err
			return
		}
		skillIndex = idx
	})

	if skillIndex == nil {
		return ""
	}

	results, err := skillIndex.Match(input, skillMatchThreshold, skillMatchLimit)
	if err != nil {
		return ""
	}
	if len(results) == 0 {
		return ""
	}

	var sb strings.Builder
	sb.WriteString("<skills>\n")
	for _, r := range results {
		sb.WriteString("<skill name=\"")
		sb.WriteString(r.Skill.Name)
		sb.WriteString("\" relevance=\"")
		sb.WriteString(formatScore(r.Score))
		sb.WriteString("\">\n")
		// Include full skill content (already includes frontmatter)
		sb.WriteString(r.Skill.Content)
		if !strings.HasSuffix(r.Skill.Content, "\n") {
			sb.WriteString("\n")
		}
		sb.WriteString("</skill>\n")
	}
	sb.WriteString("</skills>\n")
	return sb.String()
}

// matchTools finds tools relevant to the user's input and returns
// a hint block telling the model to call them.
func matchTools(input string) string {
	toolOnce.Do(func() {
		idx, err := newToolIndex()
		if err != nil {
			toolInitErr = err
			return
		}
		toolIndex = idx
	})

	if toolIndex == nil {
		return ""
	}

	results, err := toolIndex.Match(input, toolMatchThreshold, toolMatchLimit)
	if err != nil {
		return ""
	}
	if len(results) == 0 {
		return ""
	}

	var sb strings.Builder
	sb.WriteString("<tool-hints>\n")
	sb.WriteString("Relevant tools for this request:\n\n")
	for _, r := range results {
		sb.WriteString("→ `")
		sb.WriteString(r.Skill.Name)
		sb.WriteString("({...})` — ")
		sb.WriteString(r.Skill.Description)
		sb.WriteString("\n")
	}
	sb.WriteString("\nTo make one callable, use client_9p to load it through the agent ctl file:\n")
	sb.WriteString("client_9p(op=\"rdwr\", path=\"session/$OLLIE_SESSION_ID/agent/$OLLIE_UNAME/ctl\", data=\"tool_load <name>\")\n")
	sb.WriteString("Then call the loaded tool.\n")
	sb.WriteString("</tool-hints>\n")
	return sb.String()
}

func formatScore(s float32) string {
	// Format as percentage
	pct := int(s * 100)
	if pct > 99 {
		pct = 99
	}
	return string([]byte{'0' + byte(pct/10), '0' + byte(pct%10), '%'})
}

// newToolIndex creates a skill-compatible index from tool .meta files.
func newToolIndex() (*skills.Index, error) {
	model, err := embedding.LoadModel(skills.DefaultModelDir())
	if err != nil {
		return nil, err
	}

	toolsDir := filepath.Join(util.CfgDir(), "tools")
	entries, err := os.ReadDir(toolsDir)
	if err != nil {
		model.Close()
		return nil, err
	}

	var toolSkills []skills.Skill
	for _, entry := range entries {
		if entry.IsDir() || !strings.HasSuffix(entry.Name(), ".meta") {
			continue
		}
		metaPath := filepath.Join(toolsDir, entry.Name())
		data, err := os.ReadFile(metaPath)
		if err != nil {
			continue
		}
		var meta struct {
			Description string `json:"description"`
		}
		if json.Unmarshal(data, &meta) != nil || meta.Description == "" {
			continue
		}
		toolName := strings.TrimSuffix(entry.Name(), ".meta")
		toolSkills = append(toolSkills, skills.Skill{
			Name:        toolName,
			Description: meta.Description,
		})
	}

	return skills.NewIndexFromSkills(model, toolSkills)
}