use std::{borrow::Cow, collections::HashMap};

#[cfg(feature = "model")]
use serde::Serialize;

#[cfg(feature = "model")]
use crate::prelude::SqlSerializeResult;



pub type CowSegment<'a> = Cow<'a, str>;

#[derive(Debug)]
enum QueryBuilderInsertExceptions {
  None,
  AndOr,
}

pub struct QueryBuilder<'a> {
  segments: Vec<CowSegment<'a>>,
  parameters: HashMap<&'a str, &'a str>,

  /// this private enum is used as a marker for the next segment that will be
  /// inserted to detect if it should be cancelled/replaced or not.
  insert_exceptions: QueryBuilderInsertExceptions,
}

impl<'a> QueryBuilder<'a> {
  pub fn new() -> Self {
    QueryBuilder {
      segments: Vec::new(),
      parameters: HashMap::new(),
      insert_exceptions: QueryBuilderInsertExceptions::None,
    }
  }

  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new().create("Person:ee").build();
  ///
  /// assert_eq!(query, "CREATE Person:ee")
  /// ```
  pub fn create<T: Into<CowSegment<'a>>>(mut self, node: T) -> Self {
    self.add_segment_p("CREATE", node);

    self
  }

  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new().update("Person:ee").build();
  ///
  /// assert_eq!(query, "UPDATE Person:ee")
  /// ```
  pub fn update<T: Into<CowSegment<'a>>>(mut self, node: T) -> Self {
    self.add_segment_p("UPDATE", node);

    self
  }

  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new().select("ee:Person").build();
  ///
  /// assert_eq!(query, "SELECT ee:Person")
  /// ```
  pub fn select<T: Into<CowSegment<'a>>>(mut self, node: T) -> Self {
    self.add_segment_p("SELECT", node);

    self
  }

  /// Start a `DELETE` statement:
  /// ```sql
  /// DELETE user:John
  /// ```
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new().delete("ee:Person").build();
  ///
  /// assert_eq!(query, "DELETE ee:Person");
  /// ```
  pub fn delete<T: Into<CowSegment<'a>>>(mut self, node: T) -> Self {
    self.add_segment_p("DELETE", node);

    self
  }

  /// Start a `RELATE` statement:
  /// ```sql
  /// RELATE user:tobie->write->article:surreal SET time.written = time::now();
  /// ```
  /// _Note: the `SET` or anything after it in the example above should be added
  /// manually using the [`QueryBuilder::set()`] method._
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new().relate("user:John->likes->user:Mark").build();
  ///
  /// assert_eq!(query, "RELATE user:John->likes->user:Mark");
  /// ```
  pub fn relate<T: Into<CowSegment<'a>>>(mut self, node: T) -> Self {
    self.add_segment_p("RELATE", node);

    self
  }

  /// Start a `CONTENT` statement. Content statements often follow RELATE statements:
  /// ```sql
  /// RELATE user:tobie->write->article:surreal CONTENT {
  ///   source: 'Apple notes',
  ///   tags: ['notes', 'markdown'],
  ///   time: {
  ///     written: time::now(),
  ///   },
  /// };
  /// ```
  /// _Note: Anything before the `CONTENT` in the example above should be added
  /// manually using the [`QueryBuilder::relate()`] method._
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new().content("{ creation_time: time::now() }").build();
  ///
  /// assert_eq!(query, "CONTENT { creation_time: time::now() }");
  /// ```
  pub fn content<T: Into<CowSegment<'a>>>(mut self, json_content: T) -> Self {
    self.add_segment_p("CONTENT", json_content);

    self
  }

  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new().from("Person").build();
  ///
  /// assert_eq!(query, "FROM Person")
  pub fn from<T: Into<CowSegment<'a>>>(mut self, node: T) -> Self {
    self.add_segment_p("FROM", node);

    self
  }

  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new().select_many(&["ee:Person", "o:Order"]).build();
  ///
  /// assert_eq!(query, "SELECT ee:Person , o:Order")
  /// ```
  pub fn select_many<T: Into<CowSegment<'a>>>(mut self, nodes: &[T]) -> Self
  where
    T: Copy,
  {
    self.add_segment("SELECT");
    self.join_segments(",", "", nodes, "");

    self
  }

  /// Adds the supplied query with a comma in front of it
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new().also("ee").build();
  ///
  /// assert_eq!(query, ", ee")
  /// ```
  pub fn also<T: Into<CowSegment<'a>>>(mut self, query: T) -> Self {
    self.add_segment_p(",", query);

    self
  }

  /// Adds the given segments, separated by the given `separator` and with a `prefix`
  /// and a `suffix` added to them too.
  ///
  /// # Example
  /// ```rs
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .join_segments(",", "set", &["handle", "id"], "")
  ///   .build();
  ///
  /// assert_eq!(query, "set handle , set id");
  /// ```
  #[allow(dead_code)]
  fn join_segments<T: Into<CowSegment<'a>>>(
    &mut self, seperator: &'a str, prefix: &'a str, segments: &[T], suffix: &'a str,
  ) -> &mut Self
  where
    T: Copy,
  {
    let segments_count = segments.len();

    if segments_count <= 1 {
      for segment in segments {
        self.add_segment_ps(prefix, *segment, suffix);
      }

      return self;
    }

    for i in 0..segments_count - 1 {
      self.add_segment_ps(prefix, segments[i], suffix);
      self.add_segment(seperator);
    }

    self.add_segment_ps(prefix, segments[segments_count - 1], suffix);

    self
  }

  /// Starts a WHERE clause.
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .filter("handle = ?1")
  ///   .build();
  ///
  /// assert_eq!(query, "WHERE handle = ?1");
  /// ```
  pub fn filter<T: Into<CowSegment<'a>>>(mut self, condition: T) -> Self {
    self.add_segment_p("WHERE", condition);

    self
  }

  /// An alias for `QueryBuilder::filter`
  pub fn and_where<T: Into<CowSegment<'a>>>(self, condition: T) -> Self {
    self.filter(condition)
  }

  /// Writes a OR followed by the supplied `condition`
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .or("handle = ?1")
  ///   .build();
  ///
  /// assert_eq!(query, "OR handle = ?1");
  /// ```
  pub fn or<T: Into<CowSegment<'a>>>(mut self, condition: T) -> Self {
    match self.insert_exceptions {
      QueryBuilderInsertExceptions::AndOr => self.add_segment(condition),
      _ => self.add_segment_p("OR", condition),
    };

    self
  }

  /// Starts an AND followed by the supplied `condition`.
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .and("handle = ?1")
  ///   .build();
  ///
  /// assert_eq!(query, "AND handle = ?1");
  /// ```
  pub fn and<T: Into<CowSegment<'a>>>(mut self, condition: T) -> Self {
    match self.insert_exceptions {
      QueryBuilderInsertExceptions::AndOr => self.add_segment(condition),
      _ => self.add_segment_p("AND", condition),
    };

    self
  }

  /// Starts a SET clause.
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .set("handle = ?1")
  ///   .build();
  ///
  /// assert_eq!(query, "SET handle = ?1");
  /// ```
  pub fn set<T: Into<CowSegment<'a>>>(mut self, update: T) -> Self {
    self.add_segment_p("SET", update);

    self
  }

  /// Starts a SET clause with many fields.
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .set_many(&["handle = $1", "password = $2"])
  ///   .build();
  ///
  /// assert_eq!(query, "SET handle = $1 , password = $2");
  /// ```
  pub fn set_many<T: Into<CowSegment<'a>>>(mut self, updates: &[T]) -> Self
  where
    T: Copy,
  {
    self.add_segment("SET");
    self.join_segments(",", "", updates, "");

    self
  }

  /// Starts a FETCH clause,
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .fetch("author")
  ///   .build();
  ///
  /// assert_eq!(query, "FETCH author");
  /// ```
  pub fn fetch<T: Into<CowSegment<'a>>>(mut self, field: T) -> Self {
    self.add_segment_p("FETCH", field);

    self
  }

  /// Starts a FETCH clause with zero or more fields,
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .fetch_many(&["author", "projects"])
  ///   .build();
  ///
  /// assert_eq!(query, "FETCH author , projects");
  /// ```
  pub fn fetch_many<T: Into<CowSegment<'a>>>(mut self, fields: &[T]) -> Self
  where
    T: Copy,
  {
    self.add_segment("FETCH");
    self.join_segments(",", "", fields, "");

    self
  }

  /// Starts a GROUP BY clause,
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .group_by("author")
  ///   .build();
  ///
  /// assert_eq!(query, "GROUP BY author");
  /// ```
  pub fn group_by<T: Into<CowSegment<'a>>>(mut self, field: T) -> Self {
    self.add_segment_p("GROUP BY", field);

    self
  }

  /// Starts a GROUP BY clause with zero or more fields,
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .group_by_many(&["author", "projects"])
  ///   .build();
  ///
  /// assert_eq!(query, "GROUP BY author , projects");
  /// ```
  pub fn group_by_many<T: Into<CowSegment<'a>>>(mut self, fields: &[T]) -> Self
  where
    T: Copy,
  {
    self.add_segment("GROUP BY");
    self.join_segments(",", "", fields, "");

    self
  }

  /// Starts a ORDER BY ASC clause,
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .order_by_asc("author")
  ///   .build();
  ///
  /// assert_eq!(query, "ORDER BY author ASC");
  /// ```
  pub fn order_by_asc<T: Into<CowSegment<'a>>>(mut self, field: T) -> Self {
    self.add_segment_ps("ORDER BY", field, "ASC");

    self
  }

  /// Starts a ORDER BY ASC clause with zero or more fields,
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .order_by_asc_many(&["author", "projects"])
  ///   .build();
  ///
  /// assert_eq!(query, "ORDER BY author ASC , projects ASC");
  /// ```
  pub fn order_by_asc_many<T: Into<CowSegment<'a>>>(mut self, fields: &[T]) -> Self
  where
    T: Copy,
  {
    self.add_segment("ORDER BY");
    self.join_segments(",", "", fields, "ASC");

    self
  }

  /// Starts a ORDER BY DESC clause,
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .order_by_desc("author")
  ///   .build();
  ///
  /// assert_eq!(query, "ORDER BY author DESC");
  /// ```
  pub fn order_by_desc<T: Into<CowSegment<'a>>>(mut self, field: T) -> Self {
    self.add_segment_ps("ORDER BY", field, "DESC");

    self
  }

  /// Starts a ORDER BY DESC clause with zero or more fields,
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .order_by_desc_many(&["author", "projects"])
  ///   .build();
  ///
  /// assert_eq!(query, "ORDER BY author DESC , projects DESC");
  /// ```
  pub fn order_by_desc_many<T: Into<CowSegment<'a>>>(mut self, fields: &[T]) -> Self
  where
    T: Copy,
  {
    self.add_segment("ORDER BY");
    self.join_segments(",", "", fields, "DESC");

    self
  }

  /// Queues a condition which allows the next statement to be ignored if
  /// `condition` is `false`.
  ///
  /// Conditions can be nested, the queue works as a LIFO queue.
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .select_many(&["1", "2"])
  ///   .if_then(false, |query| query
  ///     .select_many(&["3", "4"])
  ///     // will not run:
  ///     .if_then(true, |query| query
  ///       .select_many(&["5", "6"])
  ///     )
  ///   )
  ///   .if_then(true, |query| query
  ///     .select_many(&["7", "8"])
  ///   )
  ///   .build();
  ///
  /// assert_eq!(query, "SELECT 1 , 2 SELECT 7 , 8");
  /// ```
  pub fn if_then<F>(self, condition: bool, action: F) -> Self
  where
    F: Fn(Self) -> Self,
  {
    if !condition {
      return self;
    }

    action(self)
  }

  /// Writes an AND followed by the supplied `first_condition` and any other
  /// statement added to the querybuilder in the `action` closure surrounded by
  /// parenthesis.
  ///
  /// Can be used to compose boolean expressions with grouped OR statements like so:
  /// ```sql
  /// WHERE name contains 'John' AND (name contains 'Doe' OR name contains 'Eod')
  /// ```
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .select("*")
  ///   .from("user")
  ///   .filter("name contains 'John'")
  ///   .and_group("name contains 'Doe'", |q| {
  ///     q.or("name contains 'Eod'")
  ///   })
  ///   .build();
  ///
  /// assert_eq!(query, "SELECT * FROM user WHERE name contains 'John' AND ( name contains 'Doe' OR name contains 'Eod' )");
  /// ```
  pub fn and_group<F, T: Into<CowSegment<'a>>>(mut self, first_condition: T, action: F) -> Self
  where
    F: Fn(Self) -> Self,
  {
    self.add_segment_p("AND", "(");
    self.add_segment(first_condition);
    let mut output = action(self);
    output.add_segment(")");

    output
  }

  /// Pushes raw text to the buffer
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .raw("foo bar")
  ///   .build();
  ///
  /// assert_eq!(query, "foo bar");
  /// ```
  pub fn raw(mut self, text: &'a str) -> Self {
    self.add_segment(text);

    self
  }

  /// Start a queue where all of the new pushed actions are separated by commas.
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .commas(|query| query
  ///     .raw("foo")
  ///     .raw("bar")
  ///   ).build();
  ///
  /// assert_eq!(query, "foo , bar");
  /// ```
  pub fn commas<F>(mut self, action: F) -> Self
  where
    F: Fn(Self) -> Self,
  {
    let other = action(QueryBuilder::new());

    for (index, segment) in other.segments.into_iter().enumerate() {
      if index <= 0 {
        self.segments.push(segment);
      } else {
        self.add_segment(",");
        self.segments.push(segment);
      }
    }

    self
  }

  /// Start a queue where all of the new pushed actions are separated by `AND`s.
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .ands(|query| query
  ///     .raw("foo")
  ///     .raw("bar")
  ///   ).build();
  ///
  /// assert_eq!(query, "foo AND bar");
  /// ```
  pub fn ands<F>(mut self, action: F) -> Self
  where
    F: Fn(Self) -> Self,
  {
    let other = action(QueryBuilder::new());

    for (index, segment) in other.segments.into_iter().enumerate() {
      if index <= 0 {
        self.segments.push(segment);
      } else {
        self = self.and(segment);
      }
    }

    self
  }

  /// Start a queue where all of the new pushed actions are separated by `OR`s.
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .ors(|query| query
  ///     .raw("foo")
  ///     .raw("bar")
  ///   ).build();
  ///
  /// assert_eq!(query, "foo OR bar");
  /// ```
  pub fn ors<F>(mut self, action: F) -> Self
  where
    F: Fn(Self) -> Self,
  {
    let other = action(QueryBuilder::new());

    for (index, segment) in other.segments.into_iter().enumerate() {
      if index <= 0 {
        self.add_segment(segment);
      } else {
        self = self.or(segment);
      }
    }

    self
  }

  /// Start a LIMIT clause.
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  ///
  /// let page_size = 10.to_string();
  /// let query = QueryBuilder::new()
  ///   .limit(&page_size)
  ///   .build();
  ///
  /// assert_eq!(query, "LIMIT 10")
  ///
  /// ```
  pub fn limit<T: Into<CowSegment<'a>>>(mut self, limit: T) -> Self {
    self.add_segment_p("LIMIT", limit);

    self
  }

  /// Start a START AT clause.
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  ///
  /// let page_size = 10.to_string();
  /// let query = QueryBuilder::new()
  ///   .start_at(&page_size)
  ///   .build();
  ///
  /// assert_eq!(query, "START AT 10")
  ///
  /// ```
  pub fn start_at<T: Into<CowSegment<'a>>>(mut self, offset: T) -> Self {
    self.add_segment_p("START AT", offset);

    self
  }

  /// Add the given segment to the internal buffer. This is a rather internal
  /// method that is set public for special cases, you should prefer using the `raw`
  /// method instead.
  pub fn add_segment<T: Into<CowSegment<'a>>>(&mut self, segment: T) -> &mut Self {
    let into = segment.into();

    if into.is_empty() {
      return self;
    }

    match (&self.insert_exceptions, into.as_ref()) {
      // if the previous segment is already a OR or an AND and the new one is
      // one of the two again, the new one replaces the old one:
      (QueryBuilderInsertExceptions::AndOr, "AND" | "OR") => {
        if let Some(last) = self.segments.last_mut() {
          *last = into;
        }

        return self;
      }
      (_, "AND" | "OR") => {
        self.insert_exceptions = QueryBuilderInsertExceptions::AndOr;
      }
      _ => {
        self.insert_exceptions = QueryBuilderInsertExceptions::None;
      }
    };

    self.segments.push(into);

    self
  }

  fn add_segment_p<T: Into<CowSegment<'a>>>(&mut self, prefix: &'a str, segment: T) -> &mut Self {
    self.add_segment(prefix).add_segment(segment)
  }

  fn add_segment_ps<T: Into<CowSegment<'a>>>(
    &mut self, prefix: &'a str, segment: T, suffix: &'a str,
  ) -> &mut Self {
    self.add_segment_p(prefix, segment).add_segment(suffix)
  }

  /// Add a parameter and its value to the query that will be used to replace all
  /// occurences of `key` into `value` when the `build` method is called.
  ///
  /// **IMPORTANT** Do not use this for user provided data, the input is not sanitized
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let query = QueryBuilder::new()
  ///   .select("{{field}}")
  ///   .from("Account")
  ///   .param("{{field}}", "id")
  ///   .build();
  ///
  /// assert_eq!("SELECT id FROM Account", query);
  /// ```
  pub fn param(mut self, key: &'a str, value: &'a str) -> Self {
    self.parameters.insert(key, value);

    self
  }

  pub fn build(self) -> String {
    let mut output = self.segments.join(" ");

    for (key, value) in self.parameters {
      let key_size = key.len();

      while let Some(index) = output.find(key) {
        output.replace_range(index..index + key_size, value);
      }
    }

    output
  }

  /// Start a SET statement with all the public fields in the supplied `T` using
  /// the [SqlFieldSerializer] and Serde to list all the serializable fields in order
  /// to get a statement like the following:
  /// ```sql
  /// SET field_one = $field_one , field_two = $field_two
  /// ```
  ///
  /// The function is meant to be used with the models generated by the [model]
  /// macro.
  #[cfg(feature = "model")]
  pub fn set_model<T: Serialize>(mut self, model: &T) -> SqlSerializeResult<Self> {
    let parameters = crate::model::to_parameters(model)?;

    self.add_segment_p("SET", parameters);

    Ok(self)
  }

  /// Start an UPDATE statement with all the public fields in the supplied `T` using
  /// the [SqlFieldSerializer] and Serde to list all the serializable fields in order
  /// to get a statement like the following:
  /// ```sql
  /// UPDATE field_one = $field_one , field_two = $field_two
  /// ```
  ///
  /// The function is meant to be used with the models generated by the [model]
  /// macro.
  #[cfg(feature = "model")]
  pub fn update_model<T: Serialize>(mut self, model: &T) -> SqlSerializeResult<Self> {
    let parameters = crate::model::to_parameters(model)?;

    self.add_segment_p("UPDATE", parameters);

    Ok(self)
  }

  /// Allows passing a custom injecter in a chainable way. The injecter will add
  /// its related SQL to the querybuilder and then pass out the resulting builder
  /// so it can be chained again.
  ///
  /// Note that injecters often avoid writing the values into the builder to avoid
  /// SQL injections, and so it is expected you use the [bindings] function to
  /// extract the variables out of the injecters afterward.
  ///
  /// # Example
  /// ```
  /// use surreal_simple_querybuilder::prelude::*;
  ///
  /// let filter = Where(("name", "john"));
  /// let query = QueryBuilder::new()
  ///   .select("*")
  ///   .from("user")
  ///   .injecter(&filter) // <-- pass the injecter to the builder
  ///   .build();
  ///
  /// let _params = bindings(filter); // <-- get the variables so you can bind them
  ///
  /// assert_eq!(query, "SELECT * FROM user WHERE name = $name");
  /// ```
  #[cfg(feature = "params")]
  pub fn injecter(self, injecter: &impl QueryBuilderInjecter<'a>) -> Self {
    injecter.inject(self)
  }
}