package main

import (
	"bytes"
	"database/sql"
	"errors"
	"fmt"
	"strings"
	"text/template"
	"time"

	"github.com/araddon/dateparse"
	"github.com/thoas/go-funk"
)

func (a *goBlog) checkPost(p *post) (err error) {
	if p == nil {
		return errors.New("no post")
	}
	now := time.Now()
	// Fix content
	p.Content = strings.TrimSuffix(strings.TrimPrefix(p.Content, "\n"), "\n")
	// Fix date strings
	if p.Published != "" {
		p.Published, err = toLocal(p.Published)
		if err != nil {
			return err
		}
	}
	if p.Updated != "" {
		p.Updated, err = toLocal(p.Updated)
		if err != nil {
			return err
		}
	}
	// Check status
	if p.Status == "" {
		p.Status = statusPublished
	}
	// Cleanup params
	for key, value := range p.Parameters {
		if value == nil {
			delete(p.Parameters, key)
			continue
		}
		allValues := []string{}
		for _, v := range value {
			if v != "" {
				allValues = append(allValues, v)
			}
		}
		if len(allValues) >= 1 {
			p.Parameters[key] = allValues
		} else {
			delete(p.Parameters, key)
		}
	}
	// Check blog
	if p.Blog == "" {
		p.Blog = a.cfg.DefaultBlog
	}
	if _, ok := a.cfg.Blogs[p.Blog]; !ok {
		return errors.New("blog doesn't exist")
	}
	// Check if section exists
	if _, ok := a.cfg.Blogs[p.Blog].Sections[p.Section]; p.Section != "" && !ok {
		return errors.New("section doesn't exist")
	}
	// Check path
	if p.Path != "/" {
		p.Path = strings.TrimSuffix(p.Path, "/")
	}
	if p.Path == "" {
		if p.Section == "" {
			p.Section = a.cfg.Blogs[p.Blog].DefaultSection
		}
		if p.Slug == "" {
			random := generateRandomString(5)
			p.Slug = fmt.Sprintf("%v-%02d-%02d-%v", now.Year(), int(now.Month()), now.Day(), random)
		}
		published, _ := dateparse.ParseLocal(p.Published)
		pathTmplString := a.cfg.Blogs[p.Blog].Sections[p.Section].PathTemplate
		if pathTmplString == "" {
			return errors.New("path template empty")
		}
		pathTmpl, err := template.New("location").Parse(pathTmplString)
		if err != nil {
			return errors.New("failed to parse location template")
		}
		var pathBuffer bytes.Buffer
		err = pathTmpl.Execute(&pathBuffer, map[string]interface{}{
			"BlogPath": a.getRelativePath(p.Blog, ""),
			"Year":     published.Year(),
			"Month":    int(published.Month()),
			"Day":      published.Day(),
			"Slug":     p.Slug,
			"Section":  p.Section,
		})
		if err != nil {
			return errors.New("failed to execute location template")
		}
		p.Path = pathBuffer.String()
	}
	if p.Path != "" && !strings.HasPrefix(p.Path, "/") {
		return errors.New("wrong path")
	}
	return nil
}

func (a *goBlog) createPost(p *post) error {
	return a.createOrReplacePost(p, &postCreationOptions{new: true})
}

func (a *goBlog) replacePost(p *post, oldPath string, oldStatus postStatus) error {
	return a.createOrReplacePost(p, &postCreationOptions{new: false, oldPath: oldPath, oldStatus: oldStatus})
}

type postCreationOptions struct {
	new       bool
	oldPath   string
	oldStatus postStatus
}

func (a *goBlog) createOrReplacePost(p *post, o *postCreationOptions) error {
	// Check post
	if err := a.checkPost(p); err != nil {
		return err
	}
	// Save to db
	if err := a.db.savePost(p, o); err != nil {
		return err
	}
	// Trigger hooks
	if p.Status == statusPublished {
		if o.new || o.oldStatus == statusDraft {
			defer a.postPostHooks(p)
		} else {
			defer a.postUpdateHooks(p)
		}
	}
	// Reload router
	return a.reloadRouter()
}

// Save check post to database
func (db *database) savePost(p *post, o *postCreationOptions) error {
	// Check
	if !o.new && o.oldPath == "" {
		return errors.New("old path required")
	}
	// Lock post creation
	db.pcm.Lock()
	defer db.pcm.Unlock()
	// Build SQL
	var sqlBuilder strings.Builder
	var sqlArgs = []interface{}{dbNoCache}
	// Start transaction
	sqlBuilder.WriteString("begin;")
	// Delete old post
	if !o.new {
		sqlBuilder.WriteString("delete from posts where path = ?;")
		sqlArgs = append(sqlArgs, o.oldPath)
	}
	// Insert new post
	sqlBuilder.WriteString("insert into posts (path, content, published, updated, blog, section, status) values (?, ?, ?, ?, ?, ?, ?);")
	sqlArgs = append(sqlArgs, p.Path, p.Content, p.Published, p.Updated, p.Blog, p.Section, p.Status)
	// Insert post parameters
	for param, value := range p.Parameters {
		for _, value := range value {
			if value != "" {
				sqlBuilder.WriteString("insert into post_parameters (path, parameter, value) values (?, ?, ?);")
				sqlArgs = append(sqlArgs, p.Path, param, value)
			}
		}
	}
	// Commit transaction
	sqlBuilder.WriteString("commit;")
	// Execute
	if _, err := db.exec(sqlBuilder.String(), sqlArgs...); err != nil {
		if strings.Contains(err.Error(), "UNIQUE constraint failed: posts.path") {
			return errors.New("post already exists at given path")
		}
		return err
	}
	// Update FTS index
	db.rebuildFTSIndex()
	return nil
}

func (a *goBlog) deletePost(path string) error {
	p, err := a.db.deletePost(path)
	if err != nil || p == nil {
		return err
	}
	defer a.postDeleteHooks(p)
	return a.reloadRouter()
}

func (db *database) deletePost(path string) (*post, error) {
	if path == "" {
		return nil, nil
	}
	p, err := db.getPost(path)
	if err != nil {
		return nil, err
	}
	_, err = db.exec("delete from posts where path = @path", sql.Named("path", p.Path))
	if err != nil {
		return nil, err
	}
	db.rebuildFTSIndex()
	return p, nil
}

type postsRequestConfig struct {
	search                                      string
	blog                                        string
	path                                        string
	limit                                       int
	offset                                      int
	sections                                    []string
	status                                      postStatus
	taxonomy                                    *taxonomy
	taxonomyValue                               string
	parameter                                   string
	parameterValue                              string
	publishedYear, publishedMonth, publishedDay int
	randomOrder                                 bool
}

func buildPostsQuery(c *postsRequestConfig) (query string, args []interface{}) {
	args = []interface{}{}
	selection := "select p.path as path, coalesce(content, '') as content, coalesce(published, '') as published, coalesce(updated, '') as updated, coalesce(blog, '') as blog, coalesce(section, '') as section, coalesce(status, '') as status, coalesce(parameter, '') as parameter, coalesce(value, '') as value "
	table := "posts"
	if c.search != "" {
		table = "posts_fts(@search)"
		args = append(args, sql.Named("search", c.search))
	}
	if c.status != "" && c.status != statusNil {
		table = "(select * from " + table + " where status = @status)"
		args = append(args, sql.Named("status", c.status))
	}
	if c.blog != "" {
		table = "(select * from " + table + " where blog = @blog)"
		args = append(args, sql.Named("blog", c.blog))
	}
	if c.parameter != "" {
		table = "(select distinct p.* from " + table + " p left outer join post_parameters pp on p.path = pp.path where pp.parameter = @param "
		args = append(args, sql.Named("param", c.parameter))
		if c.parameterValue != "" {
			table += "and pp.value = @paramval)"
			args = append(args, sql.Named("paramval", c.parameterValue))
		} else {
			table += "and length(coalesce(pp.value, '')) > 1)"
		}
	}
	if c.taxonomy != nil && len(c.taxonomyValue) > 0 {
		table = "(select distinct p.* from " + table + " p left outer join post_parameters pp on p.path = pp.path where pp.parameter = @taxname and lower(pp.value) = lower(@taxval))"
		args = append(args, sql.Named("taxname", c.taxonomy.Name), sql.Named("taxval", c.taxonomyValue))
	}
	if len(c.sections) > 0 {
		table = "(select * from " + table + " where section in ("
		for i, section := range c.sections {
			if i > 0 {
				table += ", "
			}
			named := fmt.Sprintf("section%v", i)
			table += "@" + named
			args = append(args, sql.Named(named, section))
		}
		table += "))"
	}
	if c.publishedYear != 0 {
		table = "(select * from " + table + " p where substr(p.published, 1, 4) = @publishedyear)"
		args = append(args, sql.Named("publishedyear", fmt.Sprintf("%0004d", c.publishedYear)))
	}
	if c.publishedMonth != 0 {
		table = "(select * from " + table + " p where substr(p.published, 6, 2) = @publishedmonth)"
		args = append(args, sql.Named("publishedmonth", fmt.Sprintf("%02d", c.publishedMonth)))
	}
	if c.publishedDay != 0 {
		table = "(select * from " + table + " p where substr(p.published, 9, 2) = @publishedday)"
		args = append(args, sql.Named("publishedday", fmt.Sprintf("%02d", c.publishedDay)))
	}
	tables := " from " + table + " p left outer join post_parameters pp on p.path = pp.path "
	sorting := " order by p.published desc "
	if c.randomOrder {
		sorting = " order by random() "
	}
	if c.path != "" {
		query = selection + tables + " where p.path = @path" + sorting
		args = append(args, sql.Named("path", c.path))
	} else if c.limit != 0 || c.offset != 0 {
		query = selection + " from (select * from " + table + " p " + sorting + " limit @limit offset @offset) p left outer join post_parameters pp on p.path = pp.path "
		args = append(args, sql.Named("limit", c.limit), sql.Named("offset", c.offset))
	} else {
		query = selection + tables + sorting
	}
	return
}

func (d *database) getPosts(config *postsRequestConfig) (posts []*post, err error) {
	// Query posts
	query, queryParams := buildPostsQuery(config)
	rows, err := d.query(query, queryParams...)
	if err != nil {
		return nil, err
	}
	// Prepare row scanning (this is a bit dirty, but it's much faster)
	postsMap := map[string]*post{}
	var postsOrder []string
	var path, parameterName, parameterValue string
	columns, _ := rows.Columns()
	rawBuffer := make([]sql.RawBytes, len(columns))
	scanArgs := make([]interface{}, len(columns))
	for i := range rawBuffer {
		scanArgs[i] = &rawBuffer[i]
	}
	for rows.Next() {
		if err = rows.Scan(scanArgs...); err != nil {
			return nil, err
		}
		path = string(rawBuffer[0])
		parameterName = string(rawBuffer[7])
		parameterValue = string(rawBuffer[8])
		if p, ok := postsMap[path]; ok {
			// Post already exists, add parameter
			p.Parameters[parameterName] = append(p.Parameters[parameterName], parameterValue)
		} else {
			// Create new post, fill and add to map
			p := &post{
				Path:       path,
				Content:    string(rawBuffer[1]),
				Published:  toLocalSafe(string(rawBuffer[2])),
				Updated:    toLocalSafe(string(rawBuffer[3])),
				Blog:       string(rawBuffer[4]),
				Section:    string(rawBuffer[5]),
				Status:     postStatus(string(rawBuffer[6])),
				Parameters: map[string][]string{},
			}
			if parameterName != "" {
				p.Parameters[parameterName] = append(p.Parameters[parameterName], parameterValue)
			}
			postsMap[path] = p
			postsOrder = append(postsOrder, path)
		}
	}
	// Copy map items to list, because map has a random order
	for _, path = range postsOrder {
		posts = append(posts, postsMap[path])
	}
	return posts, nil
}

func (d *database) getPost(path string) (*post, error) {
	posts, err := d.getPosts(&postsRequestConfig{path: path})
	if err != nil {
		return nil, err
	} else if len(posts) == 0 {
		return nil, errPostNotFound
	}
	return posts[0], nil
}

func (d *database) getDrafts(blog string) []*post {
	ps, _ := d.getPosts(&postsRequestConfig{status: statusDraft, blog: blog})
	return ps
}

func (d *database) countPosts(config *postsRequestConfig) (count int, err error) {
	query, params := buildPostsQuery(config)
	query = "select count(distinct path) from (" + query + ")"
	row, err := d.queryRow(query, params...)
	if err != nil {
		return
	}
	err = row.Scan(&count)
	return
}

func (d *database) allPostPaths(status postStatus) ([]string, error) {
	var postPaths []string
	rows, err := d.query("select path from posts where status = @status", sql.Named("status", status))
	if err != nil {
		return nil, err
	}
	var path string
	for rows.Next() {
		_ = rows.Scan(&path)
		if path != "" {
			postPaths = append(postPaths, path)
		}
	}
	return postPaths, nil
}

func (a *goBlog) getRandomPostPath(blog string) (string, error) {
	sections, ok := funk.Keys(a.cfg.Blogs[blog].Sections).([]string)
	if !ok {
		return "", errors.New("no sections")
	}
	posts, err := a.db.getPosts(&postsRequestConfig{randomOrder: true, limit: 1, blog: blog, sections: sections})
	if err != nil {
		return "", err
	} else if len(posts) == 0 {
		return "", errPostNotFound
	}
	return posts[0].Path, nil
}

func (d *database) allTaxonomyValues(blog string, taxonomy string) ([]string, error) {
	var values []string
	rows, err := d.query("select distinct pp.value from posts p left outer join post_parameters pp on p.path = pp.path where pp.parameter = @tax and length(coalesce(pp.value, '')) > 1 and blog = @blog and status = @status", sql.Named("tax", taxonomy), sql.Named("blog", blog), sql.Named("status", statusPublished))
	if err != nil {
		return nil, err
	}
	for rows.Next() {
		var value string
		_ = rows.Scan(&value)
		values = append(values, value)
	}
	return values, nil
}

type publishedDate struct {
	year, month, day int
}

func (d *database) allPublishedDates(blog string) (dates []publishedDate, err error) {
	rows, err := d.query("select distinct substr(published, 1, 4) as year, substr(published, 6, 2) as month, substr(published, 9, 2) as day from posts where blog = @blog and status = @status and year != '' and month != '' and day != ''", sql.Named("blog", blog), sql.Named("status", statusPublished))
	if err != nil {
		return nil, err
	}
	for rows.Next() {
		var year, month, day int
		err = rows.Scan(&year, &month, &day)
		if err != nil {
			return nil, err
		}
		dates = append(dates, publishedDate{year, month, day})
	}
	return
}

func (db *database) usesOfMediaFile(name string) (count int, err error) {
	query := "select count(distinct path) from (select path from posts where instr(content, @name) > 0 union all select path from post_parameters where instr(value, @name) > 0)"
	row, err := db.queryRow(query, sql.Named("name", name))
	if err != nil {
		return 0, err
	}
	err = row.Scan(&count)
	if err != nil {
		return 0, err
	}
	return count, nil
}